30383473 Automotive Aircnditioning Training Manual

Automotive Air Conditioning

Training Manual

Compiled by David Townley. Illustrated by Dean Tingate & Glen Burchfield

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Page 3Air Conditioning Training Manual

Company Profile

Air International was established in 1967 as a privatecompany. The venture was floated to the public in1982 and merged with Futuris Corporation Limitedin December 1990.

As the automotive arm of parent Futuris CorporationLimited, the Air International Group of Companieshas succeeded in developing substantial markets forautomotive, bus and mobile air conditioning andheating systems; specialised heavy duty air conditioning equipment; electronics; heating andrefrigeration hoses, metal fabrication; and steeringsystems.

International

ChinaShanghai Wanzhong Air International Co. Ltd76 Gui De RoadSongjiang 201600ShanghaiPeoples Republic of China

MalaysiaAPM Coachair Sbn BhdLot 3 Jalan Perusahaan Satu68100 Batu CavesSelangor Darul Ehsan (DE)Malaysia

ThailandCoachair Thailand Co. Ltd147/255-256 Pinkloa-nakornchaisri RoadSouthern Bus TerminalBankoknoi, Bangkok 10700Thailand

IndiaVoltas - AIG Ltd,5/4 Nagar Road,Pune 411 014,India

Australia

Air International Pty, Ltd(Head Office, Port Melbourne)80 Turner Street,Port Melbourne, Vic, 3207Australia.

Divisions:

Air International Pty, Ltd(Golden Grove)Golden Grove RoadGolden Grove, South Australia, 5125Australia

Steering Systems Australia Pty LtdGolden Grove Road,Golden Grove, South Australia, 5125Australia

AIM Metals Pty, LtdGolden Grove Road,Golden Grove, South Australia, 5125Australia

Hose & Pipe80 Turner StreetPort Melbourne, Victoria, 3207Australia

Air International Transit Pty, Ltd4 Bachell AvenueLidcombe New South Wales, 2141Australia

Air International Group comprises six manufacturingdivisions identified by their specific skills and disciplines - Air International Pty Ltd, SteeringSystems Australia, Air International Transit, AimMetals and Hose and Pipe. The Group also has fivejoint ventures - Shanghai Wanzhong Air International,China; Voltas - AIG Ltd, India; Automotive ClimateSystems, United Kingdom, Coachair Thailand,Thailand; and APM Coachair, Malaysia.

The company has its head office in Melbourne(Victoria, Australia) and maintains a world wide network of operations.

*

Air Conditioning Training Manual

Index

Page 4

Main Menu 2

Company Profile 3

Glossary 11

Section (I) Theory 15

Section (II) System Types 25

Section (III) Components 29

Section (IV) Retrofitting 65

Section (V) Equipment 70

Section (VI) Servicing 75

INDEXClick Logo at top of any

page to return here

Section (1) Theory

INDEX


The Four Major Functions 15

Understanding Heat 16

Change of State 19

Pressure & Temperature Relationship 20

The Ozone Layer 21

R134a Properties 22

Principles of Air Conditioning 24

Index

Section (11) System Types

INDEX


Index

CCTXV with Block Valve 25

CCTXV with Parallel Flow Condenser 26

CCOT with Parallel Flow Condenser 27

CCOT TXV Dual System 28

Section (111) Components

INDEX


Index

Compressors -------------------- 29

Clutches --------------------------- 34

Lubrication ----------------------- 35

Condensers ---------------------- 36

Foam Seals ----------------------- 37

Condenser Electric Fans ---- 37

Evaporators ---------------------- 38

Thermal Expansion Valves -39

Super Heat ----------------------- 41

Orifice Tubes -------------------- 42

Filter Drier Receivers -------------------------- 43

Accumulators ------------------------------------- 44

‘O’ Rings -------------------------------------------- 45

Hoses ------------------------------------------------- 46

Charging Ports ------------------------------------ 47

Wiring A/C systems ----------------------------- 48

Blower Speed Controls ------------------------ 49

Compressor Cycling Control ---------------- 50

Protective Sensors ------------------------------ 54

Temperature Control -------------------------- 60

Mode Control ------------------------------------- 61

Electronic Temperature Control (ECC)- 63

Section (1V) Retrofitting

INDEX


Index

Introduction 65

Procedures 66

Retro Chart 68

Section (V) Equipment

INDEX


Index

Charging 70

Combination Units 71

Gauges 72

Recovery & Recycle 73

Vacuum Pump 74

INDEX

Page 10

Section (V1) Servicing


Index

Refrigerant Safety------------------------------------------------------------- 75

Leak Detection ---------------------------------------------------------------- 76

Lubrication ---------------------------------------------------------------------- 79

Lubricating Oil ----------------------------------------------------------------- 80

System Flushing --------------------------------------------------------------- 81

Preparation ---------------------------------------------------------------------- 82

Pressure Gauges --------------------------------------------------------------- 83

Evacuation & Charging Procedure ------------------------------------- 84

Thermistor & Amplifier Testing ----------------------------------------- 86

Diagnostics ---------------------------------------------------------------------- 87

Diagnostics Hints -------------------------------------------------------------- 99


INDEXGlossary

Air Conditioner: A device used to controlthe temperature, humidity and movement of air.

Air Pressure: The pressure exerted in everydirection at any given point. Normal atmospheric pressure (pressure caused by theweight of the atmosphere) at sea level is 1 BAR(14.5037 psi).

Ambient Temperature: The temperature ofair around an object; the outside temperature.

Bar: International metric measurement unit ofpressure.

Binary Pressure Switch: A pressure activated contact switch with two functions,normally high and low pressure compressorclutch cut off.

Blower: A motor and fan that draws in air andforces it through the heater and/or evaporatorcores and into the cabin.

Boiling Point: The temperature and pressureat which a liquid changes to gas.

Bulk Charging: Use of large containers of refrigerant for charging a refrigerant system.

Capillary Tube: A hollow tube filled with refrigerant, part of the thermostatic switch or TX valve. Operates the switch or valve viatemperature changes on the capillary tube, resulting in refrigerant expansion or contraction.

Carbon Dioxide: A colourless, odourless,inert gas that can be used to purge light contaminate (for example, dust) from air conditioner parts.

CFM: Cubic Feet per Minute.

Charge: The act of placing refrigerant or oil inthe air conditioning system. Also a specificamount of refrigerant or oil by volume or weight.

Cold: The absence of heat (the lowest possibletemperature is -273.15° C below zero (-459.67°F)

Compressor: A pump used to draw in low pressure refrigerant gas and squeeze it into a high-temperature high-pressure gas. A second purpose of the compressor is to move refrigerantthrough the system.

Condensing: Gas changing to liquid.

Condenser: A heat exchanger that is used toremove heat from refrigerant, changing it from ahigh-pressure hot gas to a high-pressure warm liquid.

Condensing Pressure: Pressure, as read fromthe gauge at the discharge service valve; pressurefrom the discharge side of the compressor intothe condenser.

Contaminants: Anything other than refrigerantor refrigerant oil in the system. Usually meanswater in the system; when water and R134a mixhydroflouric acid is created (when water and R-12mix corrosive hydrochloric acid is produced).

Cycling Clutch System: A system which controls compressor clutch operation accordingto changes in the system pressure and evaporatorcore temperature.

Dehumidify: To remove water from the air.

Dehydrate (Evacuate): To place a high vacuumin a refrigerant system to remove all traces of wetair.

Desiccant: A drying agent used in the receiver-drier to remove water and ensure a drysystem.

Dichlorodifluomethane: The chemical name ofRefrigerant 12.


INDEXGlossary

Discharge: To bleed the refrigerant from a system by opening a valve or hose connection andletting refrigerant escape from the system. (To becaptured for recycling).

Discharge line: Connects the refrigerant compressor outlet to the condenser inlet.

Discharge Pressure: Pressure of the refrigerant at the discharge side of the compressor; high pressure side.

Discharge Service Valve: A valve on the discharge side of the compressor that allows high-side pressure to be checked and other service operations to be performed.

Drive Pulley: A ‘V’ or multi ribbed pulleyattached to the front of the engine crankshaft. Itdrives the compressor clutch pulley with a belt.

Driven Pulley: A ‘V’ or multi ribbed pulleyattached to the compressor.

Duct: A passageway for the transfer of air fromone point to another.

Evacuate (Dehydrate): To place a vacuuminside a refrigerant system to remove all traces of moisture.

Evaporate: Liquid changing to gas. (Change ofstate)

Evaporator Coil: A component in which the liquid refrigerant changes to a gas as it absorbs heat from theair.Expansion Valve: A device that regulates theflow of refrigerant through the evaporator to control temperature.

Flooding: A condition caused by too much liquid refrigerant going into the evaporator; usually caused by an expansion valve that is stuckopen.

Flushing: A process of cleaning out A/C systemswith refrigerant to remove heavy contamination.Flushing refrigerant must be collected and recycled.

Foaming: Bubbles of oil and refrigerant. Foamin the sight glass means a very low refrigerantcharge or P.A.G. oil boiling (refrigerant temperature above 70°C).

Freeze-Up: Ice forming at the expansionvalve orifice or the evaporator.

Head Pressure: Refrigerant pressure fromthe discharge side of the refrigerant compressor to the condenser. See Discharge

Pressure.

Heater Core: A heat exchanging componentin which hot engine coolant flows to heat thecabin or to modulate temperature producedby the air conditioner.

Humidity: The amount of water vapour in theair.

Hydraulic Lock: Seizing of compressor dueto liquid refrigerant in the piston bore of the compressor.

Hydrochloric Acid: A highly corrosive substance that forms when water and R-l2 mixin a refrigeration system.

Leak Detector: An electronic device or acoloured die used to detect refrigerant leakage ina refrigerant system.

Low Head Pressure: High-side pressurethat is lower than normal due to a systemproblem.

Low Pressure Switch: Disengages the compressor clutch when the system pressuredrops below a preset level.

Glossary

Magnetic Clutch: An electromagnetic coupling device used to engage or disengage the compressor.

Manifold Gauge Set: A manifold that iscomplete with gauges and charging hoses andis used to measure or test system pressures.

Micron: A unit of length equal to one-millionth of a metre. Used to measurevacuum drawn from a refrigerant system by avacuum pump.

1000 microns = I mm of mercury (mm HG)= 0.03937 inches of

mercury (in HG).

One inch of mercury equals 25.400 microns.

Moisture Indicator: A device connected in thehigh-pressure side which indicates how muchmoisture is in the system.

Nitrogen: A colourless, odourless & inert gasthat can be used to purge light contaminants (eg Dust from air conditioner parts).

Opacity: A condition that is used to describecontamination of refrigerant oil in the compressor. Fresh refrigerant oil is clear; when contaminated, it appears cloudy because of fineparticles held in suspension.

Orifice: An opening or small passage.

Overcharge: Too much refrigerant or oil in the system.

Phosgene Gas: Poisonous gas produced when R-12 contacts an open flame or some othersource of intense heat.

PSIG: Pounds per square inch gauge pressure.

Pressure Switch: A pressure activated contactswitch that can de-energise the compressorclutch when a higher or lower pressure occurs inthe system or at a medium pressure for activationof a radiator or condenser electric fan.

Receiver-Drier: A vessel containing desiccantused to absorb moisture, filter contaminants andstore refrigerant.

Refrigerant-11 (R11): A refrigerant that wasused for flushing contaminated air conditioner systems. R- 11 is an ozone depleting substancewhich must not be released into the atmosphere.

Refrigerant - 134a (R-134a): The Ozone friendly cooling agent used in automotive air-conditioning systems. Introduced 1993. See Tetrafluoroethane.

Refrigerant - 12 (R-12): The Ozone depletingcooling agent used in older automotive air-conditioning systems. Harmful to the environment. R-12 is an ozone depleting substance not to be released into the atmosphere. See Dichlorodifluomethane.

Refrigerant Cycle: The complete circulation ofrefrigerant through an air conditioning systemaccompanied by change in temperature, pressureand state.

Refrigerant Oil: Highly refined oil that is freefrom contaminants. Used within the A/C system,the oil is available to suit various types of refrigerant and compressors.

Relative Humidity: The water content of theair in relation to the total water the air can holdat a given temperature.

Resistor: A voltage dropping device, usually wire of different diameters wound into coils,which provides a means of controlling the blowerfan speeds.

Schrader Valve: A spring-loaded valve, similar to, butnot interchangeable with a car or bicycle tyre valve.Located inside the service valve fittings to hold refrigerant in the system. Special adaptors must be usedwith or within the gauge hoses to depress the shradervalve and allow testing and servicing to take place.


INDEX


INDEXGlossary

Sensor (ECC): A device/transducer that sensesair temperature, sunload and controls voltage forthe operation of automatic temperature controlunits.

Sight Glass: A window in the liquid line or filterdrier used to check the refrigerant charge. (May not be fitted to some R134a systems.)

Suction Line: The line connecting the evaporator outlet to the compressor inlet.

Suction Pressure: Compressor inlet pressure(the systems low-side pressure).

Suction Service Valve: A valve on the suctionside of the compressor that allows low-side pressure to be checked and other service operations to be performed.

Suction Side: The low-pressure area of the system extending from the expansion valve tothe compressor inlet.

Tetrafluoroethane: Refrigerant R134a.

Thermal Protection Switch: A temperatureoperated switch of the BI-METAL strip design, normally attached to the compressor housing.At a preset temperature the switch opens circuitand de-energises the compressor clutch.

Thermistor: A temperature-sensing resistor(NTC) in the evaporator case used to cycle thecompressor on and off.

Thermostatic Switch: A temperature sensi-tive switch used to control system temperatureby cycling the compressor on and off. May havefixed or variable settings.

Trinary Pressure Switch: A pressure activated contact switch with three functions,normally high and low pressure clutch cut off and condenser fan activation at medium pressure.

Undercharge: A system with insufficient refrigerant resulting in lack of cooling and possible compressor damage.

Vacuum: Refers to pressure that is less thanatmospheric pressure.

Vacuum Pump: A mechanical device used toevacuate and place a high vacuum (dehydrate) inthe refrigerant system.Vacuum Pump Oil: Special water soluble oilused in most vacuum pumps to absorb moisture.

Vapour: The gaseous state of a liquid (i.e., water).

INDEX


Theory

The Four Major Functions

Page 15

To be effective, the automotive air conditionermust control four (4) conditions within the vehicle interior :

These functions are essential if passenger comfortis to be maintained when the ambient temperatureand humidity are high.

By performing these functions, the air conditioner maintains the body comfortof the passengers.

It must cool the air It must circulate the air

It must purify the air It must dehumidify the air

Theory

Page 16

Understanding Heat


INDEX

What is Heat

To understand just how an air conditioning system works, we must first understand the natureof heat.

For a simple definition we may say that heat isenergy. The meshing of gears, the turning ofwheels cause friction which results in heat.Combustion (fire) gives off heat. The burning ofthe sun radiates heat to the earths surface.

Heat in the correct amount will provide life andcomfort. Heat in either extreme - either to muchor to little - will be uncomfortable.

The control of temperature means the control ofcomfort.

Air conditioning is a method of controlling heat.

When is Heat Hot?When is Heat Cold?

All substances contain heat!.

Something “feels” hot when it is warmer than ourown body temperature.

When something contains less heat than our bodies, we say it feels cold!

Cold is merely the removal of some heat.

Science tells us that a measurement called “Absolute Zero” is the point at which all heat isremoved from an object (approximately -273°C ).Any substance above this absolute zero temperature retains some heat.

Page 17

Theory

Understanding Heat


INDEX

All Substances Contain Heat

The average person requires a comfort zone ofapproximately 21ºC TO 26º C, with a relativehumidity of 45 to 50 %. In this temperature andhumidity range, we feel most comfortable. Allobjects within this same range are comfortable totouch.

As the temperature of anything goes above orbelow this range, we think of it as HOT or COLD.

Heat Measurement

A temperature reading gives us the heat intensity of a substance and not the actual quantityof heat.

Heat quantity is measured in “KILOCALORIES”(KCAL’s). One KCAL is the amount of heatrequired to raise the temperature of one kilogram of water one degree Celsius (at sea level ).This quantity measurement is used in air conditioning to describe heat transfer duringchanges of state.

What Causes Heat To Move?

Heat always moves from the hotter object to thecolder one. Whenever there is a transfer difference between two (2) objects, the heat energy will be transferred from the warmer objectto the cooler one until both objects stabilise at thesame temperature.

This is know as the law of heat transfer, and is thebasis of air conditioning operation.

When a hot cup of coffee is set aside for sometime, it becomes cold. Heat moves out of the hot (90ºC) coffee and into the cooler (25ºC) surrounding air. In time the coffee will reach thetemperature of the surrounding air.

100 KCAL

Ambient 25°C

90°C 25°C

Theory

Page 18

Understanding Heat


INDEX

How does heat get inside a vehicle?

When a car is driven or parked in the sun, heatenters the vehicle from many sources.

These sources include:

l Ambient air

l Sunlight

l Engine heat

l Road heat

l Transmission

l Exhaust system

All of these and other miscellaneous heat sourcesincrease the air temperature within the vehicle. Ina high ambient temperature situation, (eg on a 37o C day), the interior of a vehicle left standing inthe sun with the windows closed could reach 65-70o C!

Engine Heat

Sunload

Exhaust Heat Exhaust Heat

Road Heat

SunloadSunload

Page 19

Theory

Changes of State


INDEX

Evaporation

Is the term used when enough heat is added to aliquid substance to change it into a vapour (gas).For example, when water is boiled.

This condition occurs within the A/C evaporator.

Condensation

Is the term used to describe the opposite of theevaporation process. If you take a vapour andremove enough heat from it, a change of stateoccurs. The vapour becomes a liquid.

The change of vapour to a liquid is called condensation.

This condition occurs within the A/C condenser

Freezing

Is another change of state. Freezing results whenheat is removed from a liquid substance until itbecomes a solid. Remember that anything above-273°C still contains some heat.

In an air conditioning system freezing must be avoided. Otherwise component damage will occur.

Vapour

Liquid

é

Vapour

Liquid

é

Liquid

é

Glass

Liquid

Theory

Page 20

Pressure & Temperature Relationship


8848m

Mt Everest

Sea Level

70 C

100 C

110 kPa

To increase or decrease the boiling point of a substance, we must alter the pressure on the substance. Increasing the pressure, increases theboiling point.

To decrease the boiling point, decrease the pressure.

A good example is the automotive cooling system.

The pressure cap keeps the radiator from boilingover by increasing the pressure on the coolant.

Example :110 kPa radiator cap al lows the coolant temperature to reach 126°C before boiling.

This chart opposite shows that the boiling point ofwater can be altered by changing the pressureupon it.

As a comparison with the radiator example above.

The substance used in the air conditioning system, called refrigerant, also boils at different temperatures depending on the pressure that it isunder.

BOILING POINT OF WATER

PRESSURE PRESSUREABOVE SEA TEMPERATURE ABOVE SEA TEMPERATURE

LEVEL LEVEL

(kPA) OC kPA OC

0 100 82.7 120.1

13.8 103.4 96.5 123.1

27.6 106.8 110.3 126.8

41.4 110.1

55.2 113.4

69.0 116.8

INDEX


Theory

The Ozone Layer

Page 21

Ozone (O3) is formed in the upper atmosphere(stratosphere), approximately 10 to 50 kms abovethe earths surface.

This layer acts as a shield that protects the earthssurface from harmful ultra violet radiation comingfrom the sun.

The chlorine contained in CFC’s rise into theozone layer and destroys the ozone molecule O3.Depletion of the ozone layer can be catastrophicto human life causing problems such as -

l Skin cancer

l Eye cataracts

l Reduced immunity to disease.

l Damage to crops

l Reduced aquatic life

Background

1974 - It was first recognised that the use of chloroflurocarbons (CFC’s) was potentially having a detrimental effect on the ozone layer.

1987 - The Montreal protocol was adopted. Thisprotocol called for restrictions on the manufacture and usage of CFC’s to 1986 levels.From 1987 manufacturers could only produce thesame quantities as produced in 1986.

1990 - A second Montreal protocol meeting washeld and recommended a total phaseout of ozonedepleting refrigerant by the year 2000.

1996(Australia) - January no importation or manufacture of CFC’s.

- March, No R12 A/C kits to be sold.

2000 - Total phaseout of CFC’s.

OZ

ON

E

LAYER

Theory

Page 22

R134a Properties


INDEX

ADDS

SLIGHTLY

TO GLOBAL

WARMING

.03

MORE

HYDROSCOPIC

THAN R12

SMALLER

MOLECULAR

SIZE THAN

R12

Recognised

OEM

Refrigerant

STAYS AS A

LIQUID UNDER

PRESSURE

LOW BOILING

POINT

SOLUBLE

WITH OIL

CHANGES

STATE EASILY

AT LOW

TEMPERATURE

NON

TOXIC

OZONE

FRIENDLY

NORMALLY

NON-FLAMMABLE

R 134a

Since 1993 the Australian Automotive Industry hasand will continue to use a non-ozone-depletingrefrigerant HFC134a (hydroflourocarbon), its chemical name being Tetra Fluoroethane. We commonly refer to this refrigerant as R134a.

R134a was selected as a replacement refrigerantfor R12 (Dichlorodifluoromethane) because R12 containing chlorine, has a major effect to ozonelayer depletion.

R134a and water have the same abilities to changestate, but R134a can do this more rapidly and atmuch lower temperatures than water. At anytimeabove -26.3OC, R134a wil l change its state,

Disadvantages Advantages

becoming a vapour and absorb large quantities ofheat from inside the vehicle. This is what createsthe cooling effect you feel inside the vehicle.

R134a is stored in containers under high pressure.If it is released into the atmosphere, it will boil at -26.3OC.

Page 23

Theory

Refrigerant R134a


INDEX

R134a (HFC 134a) R12 (CFC 12)

Chemical Name Tetra Flouro Ethane Dichlorodifluro MethaneChemical Formula CH2FCF2 CCL2F2Ozone Depleting

0 1.0Potential (R11=1)

Global WarmingLess than 0.3 3.0

Potential

Boiling Point-26.3OC -29.6OC

Chemical Structure4.2 Angstroms 4.4 Angstroms

Molecular Structure

R134a Temperature/Pressure Data

TempOC Pressure kPa TempOC Pressure kPa TempOC Pressure kPa-46 -64 4 236 30 666

-38 -45 6 260 34 758

-34 -32 8 286 38 858

-30 -17 10 313 42 966

-26 0.3 12 341 46 1083

-22 20 14 371 50 1210

-18 43 16 402 54 1347

-14 69 18 434 58 1494

-10 99 20 469 60 1571

-6 133 22 505 70 2004

-2 171 24 543 80 2520

0 191 26 582 90 3133

2 213 28 623

R12 Comparison - Temperature/Pressure Data

Temp OC Pressure kPa TempOC Pressure kPa TempOC Pressure kPa

-46 -54 -6 150 30 666

-38 -32 -2 184 38 758

-30 -1 0 207 46 858

-26 11 4 248 50 966

-22 32 8 292 54 1083

-18 56 12 344 56 1210

-14 85 18 432 60 1347

-10 116 26 571

Theory

Page 24

Principles of Air Conditioning


INDEX

(CCTXV System)

High Pressure Side

Low pressure R134a vapour entering the compressor is compressed to become high pressure/temperature R134a vapour. This is thencirculated along with lubricating oil to the condenser. As the high pressure/temperaturevapour travels through the condenser, heat isreleased to the cooler ambient air passing over thecondenser tubes condensing the vapour into a liquid. This high pressure/temperature liquid thentravels through the filter drier onto the TX valvewhere a small variable orifice provides a restrictionagainst which the compressor pushes.

Low Pressure Side

Suction from the compressor pulls the highpressure/temperature liquid R134a through thesmall variable orifice of the TX valve and into thelow pressure side of the A/C system. The R134ais now under low pressure and becomes a low pressure/temperature vapour where heat from thecabin being blown over the evaporator coil surfaceis absorbed into the colder low pressure refrigerant. The R134a is then pulled through the evaporator and into the compressor. The A/Ccycle begins again as the R134a vapour is compressed and discharged under pressure.

Heat Transfer

R134a in the LOW PRESSURE side is COLD andcan absorb large quantities of heat from the air moving over the evaporator.

R134a in the HIGH PRESSURE side is HOT andthe cooler ambient air moving over the condenser can absorb heat from it.

Summary

l When the R134a pressure is low, the R134atemperature is low.

l When the R134a pressure is high, the R134a temperature is high.

Page 25

System Types

CCTXV with : TX Block Valve; Serpentine Condenser; Serpentine Evaporator

Note: Temperatures shown are examples only.


INDEX

5 co

30 co

60 co

60 co

70 co

0 co

30 co

HEAT GIVEN OFF

AMBIENT

H/P LIQUID

L/P LIQUID

H/P VAPOUR

L/P VAPOUR

INDEXSystem Types

Page 26

CCTXV with : Parallel Flow Condenser; Expansion Valve, Plate and Fin

Evaporator

5 co

30 co

60 co

60 co

70 co

0 co

30 co

HEAT GIVEN OFF

AMBIENT

H/P LIQUID

L/P LIQUID

H/P VAPOUR

L/P VAPOUR


5 co

30 co

60 co

60 co

70 co

0 co

30 co

HEAT GIVEN OFF

AMBIENT

H/P LIQUID

L/P LIQUID

H/P VAPOUR

L/P VAPOUR

Page 27

System Types

CCOT with : Orifice Tube; Accumulator; Parallel Flow Condenser;

Plate and Fin Evaporator



INDEX

Orifice

Tube

System Types

Page 28

CCTXV Dual System with: (2) Externally Equalised TX Valves; (2) Serpentine Condensers in

series; (2) Serpentine Evaporator in parallel; (2) Electrical

Refrigerant Flow Shut Off Valves



INDEX

70 co

60 co

60 co

0 co

H/P LIQUID

L/P LIQUID

H/P VAPOUR

L/P VAPOUR

REAR

ELECTRICAL

SHUT OFF

VALVE

FRONT

ELECTRICAL

SHUT OFF

VALVE

Components

Compressors


INDEX

Page 29

General

There are various makes and types of compressorsused in automotive air conditioning systems operating on R134a. The internal design could bePiston, Scroll, Wobble plate, Variable stroke orVane. Regardless, all operate as the pump in theA/C system to keep the R134a and the lubricatingoil circulating, and to increase the refrigerant pressure and thus temperature.

Sanden - Wobble Plate

A reciprocating piston, fixed displacement compressor. The pistons are operated by a wobble plate which moves them backwards andforwards in the cylinders.As the front shaft turns the wobble plate anglechanges, causing the pistons to move in and out,pulling refrigerant vapour in through the suctionside, compressing it and discharging this high pressure vapour into the condenser.

@À@À@À@À@À@À@À@À@À@À@À@À@À@À@À@À@À@À@ÀQ¢Suction/Discharge

ConnectionsConnecting

Rod

Wobble

Plate

Clutch

AssemblyCam

Rotor

Piston

Cylinder

Head

Intake/Discharge

Valves

Charge

Ports

Low Pressure

Vapour

High pressure

Vapour

Components

Page 30

Compressors


INDEX

Scroll Type - Sanden

This compressor uses a unique design with twoscrolls, one is fixed and the other is movable, bothare inter-leaved. The movable spiral is able toORBIT or oscillate without actually fully rotating.The movable scroll is connected to the input shaftvia an concentric bearing. As the movable spiraloscillates within the fixed spiral, a number of pockets are formed between the spiral. As thesepockets decrease in size the refrigerant issqueezed, the pressure increases and is dischargedthrough a reed valve at the discharge port in therear section of the compressor.

Suction

Pressure Area

Field Coil

Clutch Front

Pressure Plate

Clutch

Rotor Pulley

Fixed

ScrollMovable

Scroll

Discharge

Pressure

Area

Discharge

Valve

Compression Cycle

Components

Compressors


INDEX

Page 31

Variable Stroke - Harrison V5

The Delphi (Harrison) V5 compressor is a non-cycling variable displacement compressor.The compressor varies displacement to controlcapacity to meet A/C system demand at all operating conditions. The compressor features avariable angle wobble plate in a five (V5) cylinderaxial piston design.

Displacement is controlled by a bellows actuatedcontrol valve located in the rear cylinder head.This control valve senses and responds to the system suction pressure or A/C system demand.Through regulation of compressor crankcase

pressure, the wobble plate angle, and thereforecompressor displacement, is variable.

In general, the compressor discharge pressure ismuch greater than the compressor crankcase,which is greater than or equal to the compressorsuction pressure. At maximum displacement,compressor crankcase pressure is equal to thecompressor suction pressure. At reduced or minimum displacement, the compressorcrankcase pressure is greater than the compressorsuction pressure.

Discharge Pressure Suction Pressure Crankcase Pressure

A/C Demand Low

Reduced or

Minimum

Displacement

A/C Demand

High

Maximum

DisplacementControl

Valve

Wobble Plate

(Reduced or

Minimum

Angle)

Pivot

Wobble Plate

(Maximum Angle)

Components

Page 32

Compressors


INDEX

Rotary Vane - Panasonic

Rotary vane compressors consist of a rotor withthree or four vanes and a carefully shaped rotorhousing. As the compressor shaft rotates, thevanes and housing form chambers.

The R134a is drawn through the suction port intothese chambers, which become smaller as therotor turns. The discharge port is located at thepoint where the gas is fully compressed.

The vanes are sealed against the rotor housing bycentrifugal force and lubricating oil. The oil sump

and oil pump are located on the discharge side, sothat the high pressure forces oil through the oilpump and then onto the base of the vanes keepingthem sealed against the rotor housing.

During idle an occasional vane noise from the compressor may be heard. This is due to the timetaken for the lubricating oil to circulate throughthe A/C system.

Discharge

Port

Oil Pump

Oil

ReservoirRotor Body

Vane

Clutch

Assembly

Discharge

Valve

Compression Cycle

Components


INDEX

Compressors and Mount & Drive

Page 33

Mount & Drive

Consists of a bracket to mount the compressor tothe engine, a belt idler pulley, compressor drivebelt and possibly an extra drive pulley for thecrankshaft.

Compressor Mount

Manufactured of either plate, cast iron, steel or aluminium, this bracket should exhibit excellentnoise absorption qualities especially if using a piston type compressor.

Idler Pulley

A small pulley normally used in conjunction with abelt adjusting mechanism, also used when a belthas a long distance between pulleys to absorb belt vibrations.

Drive Pulley

Some vehicles do not have an extra pulley toaccommodate an A/C drive belt, in these cases anextra pulley is bolted onto the existing crankshaftpulley.

Power

Steering

Pump

Idler

Pulley

Compressor

Water

Pump Pulley

Crankshaft

PulleyAir Pump

Alternator

Multiple Belt Drive

Power

Steering

Pump

Idler

Pulley

Compressor

Water

Pump Pulley

Crankshaft

PulleyAir Pump

Alternator

Serpentine Belt Drive

‘V’

Groove

Poly ‘V’

Groove

Components

Page 34

Clutches


INDEX

Compressor Clutch

The clutch is designed to connect the rotor pulleyto the compressor input shaft when the field coil isenergised. The clutch is used to transmit thepower from the engine crankshaft to the compressor by means of a drive belt.

When the clutch is not engaged the compressorshaft does not rotate and refrigerant does not circulate, the rotor pulley free wheels. The fieldcoil is actually an electromagnet, once energised itdraws the pressure plate towards it, locking therotor pulley and the pressure plate together causing the compressor internals to turn, creatingpressure and circulating refrigerant.

Front PlatePulley

Retaining

Circlip

Pulley

Bearing

Field CoilPulleyAdjusting Shim

(Front Plate Air Gap)

Components

Lubrication


INDEX

Page 35

l

l

l

l

l

R134a - R12 Comparison

NEVER mix lubricating oils;

Use only PAG oils in R134a systems;

Use only mineral oils in R12 systems;

USE ONLY THE SPECIFIED OIL FOR THE SYSTEM YOU ARE WORKING ON;

Avoid contact with bare skin.

Sanden Scroll Type Compressor

Nipondenso Swash Plate Compressor

Harrison Variable Displacement V5 Compressor

Sanden Swash Plate Compressor

Matushita (Panasonic) Vane Type Compressor

l Do not allow PAG oil to contact bare skin Flush skin immediately.

l Do not allow PAG oil to contact paint work - wash immediately.

l Avoid breathing PAG oil/R134a mixture.

l PAG oil is highly hygroscopic. Open containers only when ready to use. Cap containers immediately after use.

R134a is part of the air conditioners lubrication system.

PAG (Poly alkaline glycol) oil is circulated aroundthe A/C system saturated in the refrigerant R134a.

Precautions:

l NEVER operate an A/C system without r e f r i g e r a n t a s t h e r e w i l l b e n o lubrication for the compressor and internal damage will occur.

l Use only the specified oil for the A/C system being worked on i.e. A system using a SANDEN swash plate compressor uses SP-20 PAG OIL.

Nippondenso Vane TypeCompressor

Components

Page 36

Condensers


INDEX

The Condenser function is to act as a heatexchanger and allow heat to flow from the hotrefrigerant to the cooler outside air.

R134a entering the condenser will be a high pressure high temperature vapour. As the R134avapour travels through the tubes of the condenser heat is given off to the cooler ambient air, the refrigerant vapour condenses andchanges to a liquid state.

At this point a large amount of heat is given off bythe R134a. The refrigerant will now be a hot, highpressure liquid.

l

l


As R134a operates on higher pressures, less internal flow, restrictive and improved heat rejection condensers are required.

Most manufactures select the parallel flow design for this reason.They are approximately 25% more

efficient than the serpentine condensers.

IN

High Pressure

Vapour From

Compressor

Heat Given off from

Refrigerant to cooler

surrounding air

OUT

High Pressure

Liquid to Filter

Drier

OUT

High Pressure

Liquid to Filter

Drier

IN

High Pressure

Vapour From

Compressor

Baffles

Design Types

Serpentine

This type of condenser consists of one long tube

which is coiled over and back on itself with

cooling fins added in between the tubes.

Parallel Flow Design

(Recommended for R134a)

This design is very similar to a cross flow

radiator. Instead of the refrigerant travelling

through one passage (like the serpentine type) it

can now travels across numerous passages. This

will give larger surface area for the cooler

ambient air to contact.

Serpentine Flow Parallel Flow

INDEXComponents

Condenser Electric Fan

Air Conditioning Training Manual Page 37

Most vehicles with air conditioning require an electrical fan to assist air flow, either pushing orpulling the air through the condenser, dependingon which side of the condenser the fan is placed.

The majority of vehicles using R134a require thisadditional condenser cooling due to the higheroperating pressures of R134a. Also most modern vehicles now have smaller front grilles orbumper bar openings. This causes poor air flowconditions especially at idle when A/C performance is limited by the amount of air flowover the condenser.

The condenser fan is operated with the A/Cengaged in various ways:

l Medium pressure switch;l Indirect connection to the compressor

clutch;l Via the Electronic Control Module(ECM);l Signal from the A/C switch activation.

l


Increased use (operation time) with R134a systems due to higher refrigerant temperature.

Conventional Skew

(By reversing the fan

blades it can either

push or pull the air)

Compressor

Earth

Earth

Inline 25

Amp Fuse

Power to

Compressor

Earth

Relay 30 Amp

Fan Types

Basic Circuit

Foam Seals

These seals are fitted in between the condenser andradiator to prevent the heated ambient air exitingabove, below or to the sides of the space in between(normally 25mm) the radiator and condenser.

As ambient air is drawn through the condenser bythe condenser or radiator fan, its temperatureincreases. If gaps are present between the condenserand radiator this heated air can be circulated backthrough the condenser. This results in the heated,circulated air causing performance and high pressureproblems as the system needs to contend with anincrease of air temperature.

Without Foam Seals

INDEX

Evaporators

l


Most manufacturers prefer to use the plate and fin design for R134a because of the 20%

performance increase over the serpentine design.

OUTLET

Low Pressure Vapour

INLET

Low Pressure Liquid

OUTLET

Low Pressure

Vapour to

Compressor

INLET

Low Pressure

Liquid

Serpentine Evaporator

Plate & Fin Laminated Evaporator (Recommended for R134a)

Separating

Baffles

R134a enters the evaporator coil as a coldlow pressure liquid. As this liquid passes through theevaporator coil, heat moves from the warm air blowing across the evaporator fins into the cooler refrigerant. This air that has now been cooled is thenducted into the cabin via the blower motor.

When there is enough heat to cause a change of state,a large amount of the heat moves from the air to therefrigerant. This causes the refrigerant to changefrom a low pressure cold liquid into a cold vapour.(Latent heat of evaporation)

As the warmer air blows across the evaporator fins, moisture contained in that air (humidity) will condense on the cooler evaporator fins. Condensedmoisture then runs off through the drain tubes located at the underside of the evaporator case.

Plate & Fin Laminated Evaporator

Similar operation to the parallel flow condenser werethe refrigerant has a multi flow pass creating a larger surface area.

Serpentine Evaporator

Same design as the serpentine condenser but approximately five times deeper.

Components


INDEX

Page 39

Components


Thermal Expansion Valves

1.

6.

(F3)

4.

2.

7.

8.

5.

3.

(F1)

9.

(F2)

8.

7.

2.

4.

3.

(F1)

5.

9.

(F2)1.

6.

(F3)

TXV Closed

TXV Open

A

A

High Pressure Liquid

Low Pressure Liquid

Refrigerant flow to the evaporator must be controlled to obtain maximum cooling, while ensuring that complete evaporation of the liquidrefrigerant takes place. This is accomplished bythe thermal expansion valve (TXV).

Pressures in ControlAs shown in the illustration, the TXV controls therefrigerant flow by using a system of opposing pressures which we will call:

F1 - Temperature Sensing Capillary TubeSealed tube filled with refrigerant. This refrigerantis also filled above the diaphragm (7). The capillary tube sensing bulb (3) is attached to theevaporator outlet tube surface.

F2 - Pressure Compensation TubeThis is a hollow tube connected to the evaporator outlet tube and senses the pressure ofthe R134a refrigerant leaving the evaporator coil.(Other TX valves may not use this tube as pressure is provided internally within the valve).

F3 - Pressure SpringThis spring (6) is located under the ball valve (5)

Operation

OpenWhen the evaporator outlet tube temperatureincreases, the refrigerant (3) in the capillary tubeexpands, forcing the diaphragm (7) downwardsand thus pushing pin (A) also downwards causing the ball valve (5) to move away from themetering orifice (4), allowing more R134a toenter the evaporator inlet side.

Closed

As the evaporator outlet tube becomes cooler,

the refrigerant in the capillary tube (3) contracts.

Forces F2 and F3 cause the diaphragm (7) and pin

(A) to move upward allowing the ball valve to

move towards the metering orifice (4), restricting

the R134a flow. The outlet tube gets warmer and

the process starts over.

1- From Filter Drier 6. Spring

2. To Evaporator Inlet 7. Diaphragm

3. Capillary Tube 8. Refrigerant

4. Metering Orifice 9. Pressure

5. Ball Valve Compensating Tube

1. From Filter Drier 8. Activating Pin2. To Evaporator Coil 9. Refrigerant3. From Evaporator 10. Pressure Compensation4. To Compressor under Diaphragm5. Metering Orifice 11. Metallic Diaphragm6. Ball 12. Sensing Element7. Spring

Components

Page 40

Thermal Expansion Block Valve


INDEX

The block valve differs from the previously mentioned expansion valve in that it has four passages, although the basic operation is exactlythe same. Operation of the block valve is still viarefrigerant expansion/contraction within adiaphragm (11), but not sensed through a separatetube (capillary tube). It is sensed by changes in therefrigerant temperature and pressure passingfrom the evaporator outlet through the blockvalve.

As the refrigerant from the outlet side of theevaporator passes over the sensing element(12), expansion or contraction of the refrigeranttakes place causing the activating pin (8) to movethe ball valve (6) away or closer to the meteringorifice. This allows more or less refrigerant toenter the evaporator coil inlet.

Pressures in ControlAs shown in the illustrations, the block valve controls refrigerant flow by using a system ofopposing pressures which we will call:

F1 - Temperature Sensing This is a sealed diaphragm and sensor containingrefrigerant. As refrigerant leaving the evaporatorcoil outlet passes over the sensing element (12)the refrigerant (9) above the diaphragm (11)expands moving pin (8) downwards pushing ballvalve (6) away from the metering orifice (5).

F2 - Pressure Compensation This is a passage (10) in the block valve outlet sidewhere refrigerant can build up under thediaphragm (11) to act as an opposing pressure tohelp regulate the amount of refrigerant into theevaporator coil inlet side.

F3 - Pressure SpringThis spring (7) is located under the ball valve (6)and acts as an opposing force trying to move theball valve towards the metering orifice (12) and toreduce refrigerant flow to the evaporator coilinlet.

12.

7.

F3

2.

4.3.

6.

9.

F1

1.

8.

11.

10.

F2

12.

7. F3

2.

4.3.

6.

9.

F1

1.

8.

11.

10.

F2

TXV Open

TXV Closed

5.

5.

High Low Pressure PressureLiquid Liquid

Components

Super Heat


INDEX

Page 41

At a certain point in the evaporator the R134arefrigerant is completely vapourised, after thatpoint any additional heat absorbed by the R134avapour is described as SUPER HEATED.

The value of this SUPER HEAT is the temperaturedifference above the point at which R134a liquidchanges to a vapour.

The thermal expansion valve ( TXV ) values are preset at the factory to compensate for the superheat. Ensure when a TX Valve is replaced it is ofthe type suited to the A/C system.

Saturation Temperature = The temperature atwhich refrigerant in liquid form changes to avapour at a given pressure.

Actual Temperature = The temperature of refrigerant at the evaporator outlet.

247 Kpa

5°C

Saturated

Temperature

From

FDR

10°C

To

Compressor

247 Kpa 10°C

Actual Temperature

Calculation

For Super Heat

Actual Temperature - 10°C

minus

Saturated Temperature - 5°C

Super Heat = 5°C

Example

Components

Page 42

Orifice Tube (C.C.O.T.)


INDEX

l

l


As R134a operates on higher pressures, less internal flow restrictive and improved heat rejection

condensers are required.

Most manufactures are selecting this parallel flow design for this reason.

At the orifice tube the R134a is forced to flowthrough a fine restriction (orifice). This causes apressure drop and temperature drop in the R134aentering the evaporator.

The rate of flow depends on the pressure differential across the restriction.

A fine gauze filter is located at the inlet and outlet sides of the orifice tube to filter any contaminates from passing onto the evaporator.

Orifice tubes have different size restrictions depending on the A/C system, these different sizescan be identified by the outer plastic tube colour.

From

Condenser

Fixed Small

Diameter

Bronze Tube

(Restriction)

Refrigerant Flow

Directional

Indicator

Fine Mesh

Filter Outlet

To Evaporator

‘O’ Rings

Fine Mesh

Filter Inlet


Low Pressure Liquid

Components

Filter Drier Receiver


INDEX

Page 43

l

l

l


R12 FDR’s use XH5 desiccant;

R134a FDR’s use XH7 or XH9 desiccant;

NEVER use an R12 FDR on a R134a system;

The filter drier acts as a particle filter, refrigerant

storage container and most importantly a moisture

absorber.

Moisture, temperature and R134a causes

hydroflouric and hydrochloric acid. The silica gel

beads (dessicant) located in the FDR absorb small

quantities of moisture thus preventing acid

establishment.

Most R134a filter drier's have NO sight glass. This

is because at approximately 70°C refrigerant

temperature the PAG oil will foam giving a false

impression of low gas charge. If the Filter Drier

Receiver (FDR) does utilise a sight glass ensure

correct diagnosis when viewing.

NOTE : Ensure the connection indicated

with the word “IN” is connected

to the condenser outlet.

From Condenser

High

Pressure

Liquid

To Evaporator

High

Pressure

Liquid

Strainer

Desiccant

Strainer


Components

Page 44

Accumulator (C.C.O.T)


INDEX

The function of the accumulator is to store refrigerant, filter particles, absorb moisture and separate vapourous R134a from liquid R134a.

The Normal process of the CCOT system workswhen R134a leaves the evaporator coil as a mixture of vapour and liquid. This liquid enters theaccumulator and falls to the bottom. The vapourrises to the top and continues onto the compressor. The liquid R134a in the bottom of theaccumulator gradually vaporizes off. This vapourrises, then pulls into the compressor.

l


Desiccant changed from XH5 to XH9.

Vapour Pick Up

Tube

From

Evaporator Low

Pressure

Liquid/Vapour

To Compressor

Low Pressure

Vapour

Desiccant

(XH9)

Filter

(Oil Suction Port)Liquid

Low Pressure

Liquid

High Pressure

Liquid

Components

‘O’ Rings


INDEX

Page 45

The ‘O’ ring rubber compound used on R134a A/Csystem joints, fittings and components, is a hydrogenated nitrile butadiene rubber (HNBR)and identified by the colour green.

‘O’ ring lubrication can be carried out using mineral oil. All hoses, tubes and components included in an A/C kit are pre-lubricated, as arethe ‘O’ rings supplied as a spare part. Other manufacturers could use ‘O’ rings of a differentcolour and size. Ensure that only the approved ‘O’ ring is used for the type of system being serviced or repaired.

l

l

l


R12 ‘O’rings coloured black;

NEVER use R12 ‘O’rings with R134a as the ‘O’ ring will be damaged owing to the lack of chlorine in R134a;

But you can use R134a ‘O’rings in an R12 system.

R134aR12

Components

Page 46

Hoses


INDEX

OWING TO THE SMALLER MOLECULAR SIZE AND

HIGHER OPERATING PRESSURES OF R134a, therefrigerant hose now incorporates a nylon inner lining. This is to reduce the normal refrigerant leakage that would naturally occur through theporosity of rubber hoses .

Most R134a hoses have a smaller outside diameter and thinner hose walls to improve flexibility and reduce noise levels within the A/C system.

l

l

l


NEVER use new R12 hose (unless of a barrier type) in an R134a A/C system. The PAG oil and hydrogen

contained in the R134a causes the normal R12 nitrile hoses to rapidly deteriorate;

R12 hoses have normally large outside diameters. this could create higher noise levels;

NEW R12 hoses permeate more refrigerant per year than R134a (R12 approx. 28 grams/year).

Reinforcement

Rubber

Nitrile

Rubber

Rubber

Rubber

Nitrile

Nylon

Reinforcement

R 12 R 134a

Components

Charging Ports


INDEX

Page 47

OpenClose

Charging ports are fitted onto components such ashoses, tubes and filter drier receivers.

These charge ports enable the A/C system to be serviced and tested whilst under pressure.Different size ports identify the high and low sidesof the A/C system. A plastic cap with a rubberseal, is used to close the charge port opening andavoid leakage.

A dedicated design of charging valve has also beendeveloped to suit the R134a charging ports.

Most shrader valves will leak slightly, ensure thatthe plastic protection cap is fitted. Shrader valvesdesigned for R134a must only be used in R134asystems. This is because of the seal material used.

l


Hand Wheel

(Open/Close

Shrader Valve

Charging Port

Shrader

ValveRubber Sealing

Washer Top

of Cap

Protective Cap1/4” or 3/16”

R12

R134a Quick Coupler R134a Charging Port

Shut Off

Valve

R12

Components

Page 48

Wiring A/C System


INDEX

C2

B8

Control/Wiring Layout(Series Connection)

Pressure switches are connected in series with thecompressor clutch. If an ‘under’ or ‘over’ systempressure occurs the pressure switch will ‘open circuit’ breaking the circuit to the compressorclutch.

With electronic fuel injected vehicles the ELECTRONIC CONTROL MODULE (ECM) is usuallyinterconnected into the A/C wiring circuit. Whenthe A/C switch is engaged a request signal is sentto the ECM, i f the A/C c ircu i t i s intact ,

i.e. the pressure switches are a closed circuit, theECM activates a relay by creating an earth andpower is supplied to the compressor clutch. Alsoan RPM increase generally takes place to avoidengine stall whilst at idle.

Power

Fuse

Blower

Switch

A/C

Switch

Thermostatic

Switch

Low

Pressure

Switch

High

Pressure

Switch

A/C

RelayThermal

Protector

Diode

Compressor

Clutch Field

Coil

A/C Relay

Energised only if

the ECM provides

the Earth

ECM

Components

Blower Speed Controls


INDEX

Page 49

Coil Type

This blower speed regulator simply consists ofcoiled wires connected in series. These coiledwires are of varied thickness. The current flowsthrough either one or a combination of all thecoils, the resistance of the coil(s) alter the blowerspeeds.

The highest blower speed when selected is normally from direct battery voltage via a relay.

Electronic

The function of the electronic controller is to convert low current signals from the ECM to a higher current, varying the voltage to the blowermotor. Blower speeds may be infinitely variableand usually can have up to 13 speeds.

This type of speed controller is normally used withthe electronic climate control (ECC) system.The highest blower speed when selected is normally from direct battery voltage via a relay.

Protective

Cage

Fan Speed

Resistance

Coils

Electronic

Modual

Heat

Sink

Blower

Switch

or

Control

To Blower Relay

Blower Speed 4.

IGN 12V

Coil TypeElectronic Type

Electronic Type

Coil Type

Speed 1.

Blower

Motor

+12V

2.3.

Components

Page 50

Compressor Cycling Controls


INDEX

l


No change except for probe location if a different type of evaporator used.

Bellows

filled with

Refrigerant

Capillary

Tube

Ground

Clutch

Coil

Ground

ThermostatBlower Motor

Ground

Resistor

Combination

A/C and

Blower Switch

Ignition

Switch

Switch

Point

Electrical Circuit

Thermostatic Switch (Anti Ice-up Device)

The thermostat is connected in series to the compressor clutch. When the temperature of the

evaporator coil approaches freezing 0°C, this temperature is sensed by the thermostat capillary tube which is in contact with the evaporator fins. The capillary tube containsrefrigerant, which expands or contracts dependingon the temperature on this tube. The points insidethe thermostatic switch open up when the refrigerant in the capillary tube contracts (sensinga cold evaporator coil) and interrupt the A/C electrical circuit turning the compressor off. Whenthe evaporator temperature rises again to a presetpoint (4 - 5 °C) the thermostat points then close.The refrigerant in the capillary tube has expanded(sensing a warmer evaporator coil and the electrical circuit is re-established to the compressor clutch.

Components



INDEX

Page 51

Thermistor & Amplifier

This has the same function as the thermostaticswitch except rather than mechanical action withcontact points and capillary tube, the thermistorand amplifier is electronically activated. The thermistor is a sensing probe but unlike the thermostat capillary tube it senses the air temperature coming off the evaporator coil.

ThermistorElectrical wiring containing a sensor which is aNTC Resistor (Negative Temperature Co-efficient).

AmplifierA small electronic device containing a circuit boardand electrical components. Thermistor resistanceis amplified and used to control or switch the A/Cclutch on or off.

Amplifier

Thermistor

l


No change except for probe location if a different type of evaporator used.

Economy Mode

This function is normally associated with the useof a thermistor amplifier (described above). Ineconomy (ECON) mode the compressor cut outtemperature is set higher than in the normal A/Cmode. This means the compressor stays on for alesser time, decreasing engine load and improvingfuel economy and engine performance.

Centre vent temperatures will also be slightlyhigher due to the compressor cycling off at ahigher evaporator temperature.

A/C / ECON

Switches

Components

Page 52



INDEX

A C

Pressure Cycling Switch - Electrical

Some vehicles using the Cycling Clutch OrificeTube (CCOT) system, utilise a pressure switchlocated in the low side of the A/C system between the evaporator and the compressor for compressor control.

This pressure switch is electrically connected inseries with the compressor clutch.

Once the low side pressure reaches approximately 200 kPa, the compressor clutch is deactivated by the pressure switch opening. A lowside pressure of approximately 200 kPa corresponds to an evaporator coil temperature ofapproximately + 0. 5°C (above freezing point).

Once the compressor is deactivated the low pressure rises followed by the evaporator coiltemperature rising. At a predetermined low pressure point, the pressure switch reactivates thecompressor clutch. The evaporator temperaturelowers again and the compressor re-engages.

NOTE: Normally a low pressure cut off switch isnot used with a pressure cycling switch as the pressure cycling switch is located on the low side.It serves as a low pressure cut off also.

High

Pressure

Switch

Pressure Cycling Switch

Compressor Clutch

Disengages at approx. 200kpa.

Re-engages approx. 350kpa

Components



INDEX

Page 53

Discharge Pressure Suction Pressure Crankcase Pressure

Pressure Control Valve - Mechanical

A/C Demand High - During periods of moderate to high A/C demand, system suction pressure will be greater than the controlvalve set point. During these periods, the control valvemaintains a bleed from crankcase to suction. Crankcasepressure is therefore equal to suction pressure. Thewobble plate angle, and therefore compressor displacement is at its maximum.

Discharge

Crankcase

Valve

Suction

Crankcase

Valve

Evacuated

Bellows

To

Suction

Chamber

From

Crankcase

Chamber

To

Compressor

Crankcase

From

Discharge

Chamber

Control

Valve

Crankcase

Harrison Variable Stroke Compressor

A/C Demand Low - During periods of low to moderate A/C demand, systemsuction pressure will decrease to the control valve set point.The control valve maintains a bleed from discharge tocrankcase and prevents a bleed from crankcase to suction.The wobble plate angle, and therefore compressor displacement is reduced or minimised. During these periods, displacement is infinitely variable between approximately 5 and 100% of its maximum displacement.

Thermal Protection Switch

The thermal protection switch is normally locatedon the compressor housing. This protectionswitch is used to prevent compressor damagethrough internal friction.

This switch senses the compressor case temperature and once this case temperaturereaches a predetermined figure the electrical circuit to the compressor clutch is interrupted.

As the thermal protection switch is connected inseries with the compressor clutch once the compressor case temperature lowers to a predetermined figure the compressor clutch isthen re-energised.

Components

Page 54

Protection Devices


INDEX

Clutch Diode

The clutch coil is an electromagnet with a strongmagnetic field when current is applied. This magnet field is constant as long as the clutch isapplied. When the power is removed the magnetic field collapses and creates high voltagespikes. These spikes are harmful to the ECM and

l


Different temperature settings due to higher operating pressures and temperatures.

Diode

Compressor

Clutch

Thermal

Protection

Switch

Lead

Wires

Movable

Contact

Fixed

Contact

Bimetallic

Strip

Pin

must be prevented. A diode placed across theclutch coil provides a path to ground. This diode isusually taped inside the clutch coil connector.

Components

Protection Devices


INDEX

Page 55

Refrigerant Pressure Switches

Low Pressure - Used to interrupt the electrical circuit to the compressor clutch. If the refrigerantpressure is too low or a problem exists in the A/Crefrigerant system. (refer diagram)

High Pressure - The power supply is interrupted when the refrigerant pressure is toohigh or a problem exists in the A/C refrigerant system.

Terminology

Binary Switch - High/Low switch.

Trinary Switch - High/Medium/Low switch.

Condenser Fan Control

Medium Pressure - Used to engage the condenser fan at a pre-determined refrigerant pressure.

Example: Condenser Fan high speed activation at1770kpa refrigerant pressure.

These switches can be individual or a combinationof the two or even three pressure ranges.

l

R134a - R12 Comparison - Setting Differences

Different high pressure settings due to higher operating pressures and temperatures.

R134a System = 3200 kPA (High Pressure)

R12 System = 2760KPA (High Pressure).

Refrigerant Pressure

Diaphragm

Activating

Pin

Contacts

PowerCompressor

Clutch

1770 kpa

(example)

R134a Charging Port

Components

Page 56

Protection Devices


INDEX

Pressure Transducer

The pressure transducer is a sealed gauge reference, capacitive pressure sensor with onboard signal conditioning. It provides a 0.5 voltoutput and requires a 5 volt regulated power supply.

In operation the transducer sensor applies pressure via the deflection of a two piece ceramicdiaphragm with one half being a parallel plate capacitor. Changes in capacitance influenced by therefrigerant pressure under the ceramic diaphragmare converted to an analog output by the transducers integral signal electronics.

The pressure transducer’s electronics are on aflexible circuit board contained in the upper

Ceramic

Diaphragm

section of the transducer and provide linear calibration of the capacitance signal from theceramic sensing diaphragm.

Benefits of using the pressure transducerover a normal type pressure switch is that thetransducer is constantly monitoring pressuresand sending signals to the engine controlmodule (ECM), unlike the normal type pressure switch that has an upper and lowercut out point. The ECM will disengage theA/C compressor at low or high refrigerantp r e s s u r e s a n d e l e c t r o n i c d i a g n o s t i c equipment can be used to extract systempressure information making it easier whendiagnosing problems.

Signal

Electronics

Pressure

Port

Pressure

TransducerHigh Side

Charge

Port

Pressure

Transducer

Page 57

Components

Protection Devices


INDEX

Engine Control Module (ECM)Body Control Module (BCM)Power Train Module (PCM)

Micro processors (ECM, BCM or PCM) are usedto engage and disengage the A/C electrical circuitscontrolling the compressor and condenser fan.

Numeric signals from various sensors relating toengine speed, road speed, coolant temperature,A/C switch activation, pressure switches, A/Cthermostatic switch, throttle position and kickdown are constantly being monitored by theECM, BCM or PCM. These numeric signals areconverted in the micro processors to calculationsrequired to :

- deactivate the A/C compressor at high/low system pressures;

- deactive the A/C compressor at kickdown;

- active and deactive the condenser fan;- increase engine idle speed when A/C

system is activated;- deactivate the A/C compressor at high

engine RPM;- delay A/C compressor engagement at

engine cranking;- activate electrical engine fan at

predetermined coolant temperatures- deactivate the A/C compressor when

coolant temperature excessive;- deactive the A/C compressor at wide

open throttle (WOT)

C2

B8

F6

Power

Fuse

Blower

SwitchA/C

Switch

Thermostatic

Switch

Low

Pressure

Switch

High

Pressure

Switch

A/C

Relay

Thermal

Protector

Diode

Compressor

Clutch Field

Coil

A/C Relay

Energised only

if the ECM pro-

vides the Earth

PCM

Fan Fusible

Link

Fuse

Engine Cooling

Fan Relay High

Speed

A/C Pressure

Switch

Engine Cooling

Fan Relay High

Speed Control

Two Speed Engine

Cooling Fan

BCM

Engine Cooling Fan

Relay Low Speed

Engine Cooling

Fan Relay Low

Speed Control

Components

Page 58

Protection Devices


INDEX

A/C Switch

Voltage

drop

across A/C

Switch

approx 2

Volts

10 VoltsCompressor

Clutch

Earth

Battery 12

Volts

Earth

Without Relay

With Relay

A/C Switch

Battery 12

Volts

Earth

EarthEarth

12

Volts

A/C Switch

Energises

Relay

Relay

Compressor

Clutch

Relays

Relays are normally used in the A/C electrical circuit to protect switches that have a low currentcarrying capacity (ie a small contact area/weak pressure contact point) or for current draw differences between components.

Shown below is an example of the difference in acircuit with and without a relay.

Page 59

Components

Sensors


INDEX

Sunload

The sunload sensor is a photo chemical diode(PCD) located on top of the dashboard. This sensor sends a signal to the electrical climate control module (ECCM) indicating the strength ofthe sunlight (sunload) which influences the vehicleinterior temperature.

If the sunload is high as signalled by the sunloadsensor the ECCM will activate the highest blowerfan speed and maximum cooling to compensate forthis additional radiated heat load. Likewise, if thesunload is low (cloud cover) as sensed by the sunload sensor, the ECCM will reduce the blowerfan speed and the system will not operate at maximum cooling.

Ambient Temperature Sensor

The ambient temperature sensor is a negativecoefficient resistor (NTC) with a low voltageinput. The sensor alters resistance depending onthe ambient air temperature surrounding it.

The sensor is located in the ambient air streamnormally behind the bumper bar or front grillearea. This sensor is used to monitor the outsidetemperature and is interconnected to a visual display in the instrument panel.

0

100

200

0

4 56

7

32

1

8

Ambient

Temperature

Sensor

Sunload Sensor

Components

Page 60

Temperature Control


INDEX

Air Mix Door

Temperature control is carried out by operatingthe temperature mode control, normally cableoperated and connected to a door housed in theheater case. This door is located above the heatercore and in the full cold position, completely covers the heater core. As more heat is required,the door is operated and moves away from the

heater core and allows radiant heat to rise and mixwith the fresh or A/C air to increase the vent temperatures to the desired comfort levelrequired.

Heater Control

The heater tap is normally vacuum operated andhas engine vacuum applied to it in the full coldposition. This stops the flow of coolant to theheater core by keeping the heater tap closed.

Once heating has been selected, the vacuum isexhausted from the vacuum circuit via a vacuumswitch, to the heater tap and the hot coolant thenflows through to the heater core.

Air Mix

Door

Heater

Core

Plunger

Vacuum

Switch

To Mode

Control

From

Vacuum

Source

Heater

Tap

Vacuum

Actuator

Actuating Lever

connected to the

Temperature

Control via a Rod

Air Flow during Maximum Hot Air Flow during Maximum Cold

Air Mix

Door

Heater

Core

Components

Mode Controls


INDEX

Page 61

Vacuum Actuators-Single & Duel Stage

The various air distribution duct doors located inthe heater-A/C case are open and closed using a vacuum actuator.

The vacuum actuator consists of a plastic or metalcontainer housing a spring, rubber diaphragm anda connecting rod. Once vacuum is applied, the rubber diaphragm is pulled back bringing with itthe connecting rod which is connected via a leverto an air distribution door and compressing thespring. When the vacuum is removed, the springpushes the diaphragm and connecting rod back tothe original position.

Vacuum Circuit

Vacuum is directed to the desired distribution ductvacuum actuator, from engine intake manifold vacuum.

A vacuum switch attached to the mode controlknob redirects vacuum to the desired vacuum actuator.

ÞÞ

Þ

Vacuum

Released

Vacuum

Applied

Mode

Direction

Control Mode

Vacuum

Control

Vacuum

Actuators

Vacuum Port

1st Stage

Housing

Vacuum Port

2nd Stage

Spring 2nd Stage

Diaphragm

Actuation

Rod

1st Stage

DiaphragmSpring

2nd Stage

1st Stage (Half)

Fully Extended

Single Stage

Duel Stage

Components

Page 62

Mode Controls


INDEX

Air Mix Motors

The air mix motor is actually a potentiometer balance resistor (PBR). It comprises of a small electrical motor, gears of varying sizes, a driveshaft and a printed circuit board. It is attached bymeans of a drive shaft to the air mix or temperature mode door main shaft. This motorregulates the temperature by moving the doorcloser to (cooler) or further from (hotter) theheater core.

Variable low voltage signals are sent from the electronic climate control module (ECC) to movethe air mix motor - which in turn moves the temperature mode door, to a predetermined position to regulate the vehicle interior temperature. The air mix motor position signalsare also sent back to the ECC for reference as towhere the air mix/mode door is positioned.

Vacuum Solenoid Pack

This method for operating the vacuum actuators isnormally used in conjunction with the electronicclimate control system (ECC). This type of climatic control is fully electronic. The vacuumactuators used for various air distribution modesare ind irect ly engaged and d isengaged electronically via the vacuum solenoid pack

The solenoid pack consists of a group of electrically activated vacuum solenoid valves usinga common printed circuit board while enclosed ina single housing.

Each solenoid is allotted to a vacuum actuator orvacuum valve (heater valve). Once the vacuumsolenoid is energised by the ECC, an engine supplied vacuum can then flow through the solenoid valve to the relevant vacuum actuator tooperate a mode. Likewise, once the vacuum solenoid is de-energised it then vents the vacuumfrom the line and actuator into the atmosphere.

Actuator

Vacuum Solenoid

Pack

Page 63

Components

Electronic Temperature Control (ECC)


INDEX

-88.8AMB

AMUATNOU A L A/C

C

A1 2 3

CLIMATE CONTROL

M A N U A L

0FF

MODE A/C

AMB

AUTO

ECC systems operate with the same basic components as in the manually controlled systems,such as the condenser, compressor, evaporator andheater. The major difference being that the ECC system can maintain a preset level of cooling or heating selected by the vehicles operator once theautomatic mode is selected.

Electronic sensoring devices allow the ECC torespond to various changes in sunload, interior cabin temperature and ambient temperature. The ECC system will adjust automatically to any temperatureand climatic changes, to keep the vehicle cabin interior within the pre-selected temperature range.

This is accomplished by adjusting:

l Blower fan speeds

l Air mode positions

l A/C activation

l Heater tap activation

l Air mix door movement

l Flesh/Recirc door position

Control

DisplayIn Car Temperature

Sensor

Sunload

Sensor

Ambient

Temperature

Sensor

Compressor

Vacuum

Solenoid Pack

Air Mix

Door Motor

Evaporator

Temperature SensorWater

Temperature

Sensor

Blower Speed

Resistor

Components

Page 64

Electronic Temperature Control (ECC)


INDEX

Whilst the systems main benefits are attained onthe AUTOMATIC mode, the option for manualoveride exists. But once manual mode has beenselected by pushing the fan speed, A/C or modeswitch, it takes away a function normally controlled by the processor in the ECC modulemaking the processor adjust an alternative component to attain the pre-selected temperature.

Batt +

IGN

GND

Power

Source

Circuit

5V

5V

Reset Fail

Safe Circuit

Evaporator

Ambient

Water

Intake

In Car

Sun

Air Mix

Motor

5V

Light

Illumination

Inp

ut

Inte

rface

Cir

cu

itIn

pu

t In

terf

ace C

ircu

it

An

alo

gu

e t

o D

igit

al

Co

nvert

er

Cen

tral

Pro

cess

ing U

nit

Ou

tpu

t O

pera

tio

n C

ircu

it

Key Pad

LC

D

Dri

ver

LCD

Relay

Comp.IGN

Relay

ECM

High Blower Speed Request

A/C

Request

Sensor Water Temp.

FootMode

DefrostMode

Mode Vent

Air Mix

Door

Sensor

IGN

Blower

Control

Blower Motor

IGN

Blower

Control

Component Interface

An additional benefit of the ECC system is a self diagnostic function which when used will greatlyreduce the time spent locating system faults.

Retrofitting

From Refrigerant R12 to R134a


INDEX

Page 65

Introduction

With the accelerated phase out of R12 ( 1 st January 1996 ) many compromises have tobe considered and quite possibly accepted in retrofitting R12 automotive A/C systems to operate on an alternative refrigerant such asR134a.

No direct “drop in” replacement refrigerant forR12 systems is available, even alternatives such asternary blends require the replacement of components such as hoses, ‘O’ rings, filter drier'sor accumulators.

System lubrication, Air International and the majority of automotive manufacturers are recommending PAG (Poly Alkaline Glycol ) oil asthe only oil replacement when retrofitting R12 automotive A/C systems to operate on R134arefrigerant.

It is also recommended that if an R12 A/C systemis functioning correctly and no refrigerant leaks arepresent DO NOT retrofit until absolutely necessary i.e.

- Replacing a major component such as the compressor or condenser.

- When R12 is no longer available.- Accident damage.

Cost will be a very important issue if an R134aretrofit is to be undertaken, BUT do not sacrificeperformance and reliability for the sake of cost. Asfurther documented there will be temperatureand pressure increases within the system. This willall depend on how the A/C system originally performed on R12, if the performance was marginal on R12 a retrofit to R134a WILL NOTimprove that performance.

Retrofitting the A/C system is probably the simplest part, the most important part prior toretrofitting will be the time spent talking to theowner discussing:

- What A/C repairs were last carried out and when?

- What parts were replaced?

- Is the A/C system already operating on an alternative refrigerant?

- Is the A/C functioning/operating okay presently, if not, ask the owner for any known history of problems?

- How long do they intend keeping the vehicle? This could alter the depth of retrofit? Do you replace the condenser with a more efficient design? Explain associated costs to the owner.

- What warranty will be offered on the retrofit?

- Any defects and leaks will have to be repaired before the R134a retrofit can take place. These costs will be over and above the retrofit price.

Retrofitting

Page 66

From Refrigerant R12 to R134a


INDEX

1/ Initial Inspection - A full visual inspection ofall components, hoses, signs of leakage, corrosion- also look for warning labels indicating what refrigerant is in the A/C system, an alternativerefrigerant could already have been used.

(NOTIFY THE OWNER OF EXTRA PARTS

REPLACEMENT ABOVE RETROFIT COST REQUIRED

TO BRING THE A/C SYSTEM BACK TO A FULLY

OPERATIONAL CONDITION).

2/ Performance Check - Start engine, engageA/C, operate for 10 minutes at 1500 rpm, on maxcooling and highest fan speed, insert thermometerprobe into the centre vent and connect R12 pressure gauges. If required add sufficient R12 refrigerant (if available) to bring the A/C systempressures and centre vent temperatures to themanufacturers specifications. Take note of thepressure and temperature readings.

(NOTE: RUNNING THE A/C SYSTEM FOR 10 MINS

ETC. WILL ENSURE THAT MOST OF THE MINERAL

OIL WILL BE TRAPPED IN THE COMPRESSOR).

Check condenser airflow for restrictions. obstructions, such as insect screens, grass seedsand insect build up over the condenser face, alsofor any signs of system overheat.

3/ Leak Checking - Carry out complete leakcheck (To SAE J1628) using a dedicated R12 leakdetection device. (To SAE J1627)

(NOTIFY OWNER OF EXTRA PARTS NEEDED TO BE

REPLACED ABOVE RETROFIT COSTS.)

4/ R12 Recovery- Recover refrigerant from theA/C system using a dedicated R12 recovery device(To SAE J1990).

5/ R12 Parts Replacements - Remove the components to be replaced as part of the retrofit to R134a, as recommended by the A/C system or vehicle manufacturers guidelines.

THE MINIMUM - Filter drier or accumulator;- High side system ‘o’ rings

through to the evaporator inlet;

- Remove compressor and drain off mineral oil, add PAGoil. (To SAE J1660);

- Fit high/low side R134a charging port adaptors (use a thread lock to secure to R12 charging port);

- Retrofit warning labels.

6/ Flushing Option - If when removing components contaminat ion is found ie. aluminium particles, it would be advisable toflush the system. Components such as the compressor, filter drier/accumulator and ‘o’ ringsare to be replaced. Flush all remaining components with liquid R12 (if available) collectedthrough a recovery device. Fittings will have to be manufactured for this function.

7/ Evacuation - Using R134a equipment, evacuate the A/C system for a minimum of 40 minutes at a vacuum of - 100kPa.

8/ Charging - Charge the A/C system withR134a to approx. 90% of the original R12 chargequantity eg. original R12 1000 grams, R134a retrofit charge 900 grams.

9/ Warning/Identification Labels - Remove alllabels from the vehicle referring to the REPLACEDrefrigerant. Affix new R134a warning andoil/change quantity labels (to SAE J1660) to aprominent location in the engine bay. Write onlabels all fitment information required in ballpointpen.

10/ Performance Check - Take pressure andcentre vent temperature readings, compare to the‘baseline’ information taken in step 2.

Remembering that R134a pressures will be 10 - 20% higher and centre vent temperatures possibly slightly higher also.

Retrofitting


INDEX

Page 67

11/ Road Test - Carry out road test, again checkperformance in the various fan speeds and modepositions. Ensure if in an extended idle situationthe compressor does not fast cycle on the highpressure switch (high pressure problem). If thisoccurs, especially in high ambient conditions, further work might be required, such as:

l condenser (refer page 22);

l condenser fan (refer page 23);

l condenser seals (refer page 31);

l pressure switches with higher settings (refer page 41);

l removal of insect screens, etc.

12/ Hand over - Explain to customer what exactly has been replaced, and any warranty implications.

Barrier

Hose

Parallel Flow

Condenser

Condenser

Fan

Filter Drier XH7

or XH9 Desiccant

R134a

Adaptors

CCOT System

Accumulator

XH7 or XH9

Dessicant

CCOT System

Pressure Switch

Higher Settings

R134a

Identification

Label

R12PRE RETROFIT DISCUSSION

WITH CUSTOMER

• Date of last repair to the A/C system.

• What parts were replaced, especially hoses.

• Is the system fully functioning.

• Has the A/C system been retrofitted with an alternative before.

• Costs could be incurred above the retrofit for nonretrofit parts fitted.

• Explain that higher R134a pressures could causeslightly higher vent temperatures.

• What type of driving is mostly done, city, country, longhigh speed runs, etc.

1

R12PERFORMANCE CHECK

• Connect pressure gauges.

• Run A/C system for a minimumof 10 minutes on :- highest blower speed, maximum A/C at1500 RPM.

• Mark down pressure and

temperature readings for

comparison after the retrofit.

• If low refrigerant charge is confirmed, add required amountof R12 and re-test.

3

R12A/C SYSTEM INSPECTION

VISUAL

• Damage.

• Cracked/burnt hoses.

• Oil leakage areas.

• Charge port fittings.

• Labels indicating a refrigerantother than R12 used.

• Noises such as compressor.

2

R12LEAK TEST

• Using an electronic R12 leak detector thoroughly check all components, fittings etc. for refrigerant leaks.

• Always check under componentsand fittings for refrigerant leaks asR12 is heavier than air.

4

R12REFRIGERANT

RECOVERY

• Recover the refrigerant R12 intoan R12 specified recoverymachine.

• If the accumulator or filter drierices up on the lower section afterrecovery, liquid refrigerant istrapped. Lightly warm up the areawith a hair drier and recover again.

5

R12PARTS FOUND

LEAKING IN STEP 4

• Components found leaking in Step 4 have to be replaced usingR134a specific components suchas R134a nylon barrier hoses.

• Any components replaced otherthan components required forthe R134a retrofit will be overand above the retrofit price —contact the owner for approval.

6

R12MINERAL OIL

REMOVAL

• Remove the compressor anddrain all the mineral oil by turningthe compressor upside down androtating the front plate.

IMPORTANT• Refill the compressor using the

recommended manufacturersPAG oil only.

• Adding PAG oil:- Fill the compressor through the suctionport while turning the front plate.Fill to the same oil quantity as specified for the original R12 fill.

7

R12SYSTEM

CONTAMINATION

• Inspect the interior of the discharge hose for signs of contamination such as aluminiumflakes.

• If contamination is found flushindividual components, tubes andhoses with liquid R12 collectedthrough an R12 recoverymachine.

8

Retrofitting

Page 68

Procedure


INDEX

INDEX


Retrofitting

Procedure

R134aRETROFIT COMPONENTCHANGES (THE MINIMUM)

• Change all O-Rings in the engine bayhigh and low sides to HNBR(R134a) type (green), including compressor.

• Filter drier or accumulator suitablefor R134a XH7 or XH9desiccant.

• R134a charging port adaptorssecure with threadlock.

• R134a warning and installationlabels. Remove any labels referringto R12.

• If any A/C hoses (non barriertype) have been replaced in thelast 3 months, it is recommendedthey be replaced again with barrier type hose.

9

R134aRETROFIT PARTS

REPLACEMENT CONSIDERATIONS

(This can be clarified once Step 13 completed)

• Larger condenser with improvedheat rejection.

• Condenser fan.

• High pressure switch with highercompressor cut-off setting.

• Orifice tube with smaller I.D.

• Foam seals between condenserand radiator to stop engine reheat air and ambient air bypass.

10

R134aEVACUATION

• Using an R134a deep vacuumpump evacuate the R134aretrofitted system for a minimum of 30 - 45 minutes, to avacuum of minus 100 kPA (29.8 inhg).

• Carry out a vacuum holding testto ensure no major leaks are evident.

11

R134aPERFORMANCE TESTING

AND ROAD TEST

• Carry out pressure and centre venttemperature check. Compare these figures to the ones taken in Step 3.

• Road test vehicle at various roadspeeds and fan positions . Return to anidle situation, stay at idle for 20minutes, if possible, to check effect onpressures and centre vent temperatures.

• If the pressures and temperatures areabove what is deemed acceptable compared with Step 3, contact owner and suggest alternatives such as in Step 10.

13

R134aR134a SAFETY

AND PRECAUTIONS

SAFETY• Do not inhale R134a and PAG oil.

• Do not allow PAG oil to contact bare skin.

• Work in a well ventilated area.

• Always wear gloves and glasses.

PRECAUTIONS• Keep PAG oil containers tightly capped

as PAG is highly hygroscopic.

• Do not overcharge the system. Do notrely on the filter drier sightglass whencharging.

• Ensure there is no air in the A/C system. Excessive air can make R134a combustible.

• Do not allow PAG oil to contact vehiclepaint work.

R134aCHARGING

• Using an R134a charging station refillthe A/C system to 90% of the originalR12 refrigerant charge.

• Example:- R12 = 1000grams90% — R134a = 900grams

• Disregard the filter drier sight glass (iffitted) as this could provide a false indication (PAG oilfoaming).

• Carry out complete leak check usingan R134a electronic leak detector.Check under fittings and components.

12

R134aHAND OVER TO

CUSTOMER

• Explain to customer exactly whathas been replaced.

• Show the R134a warning labelsand charging ports, now indicat-ing only R134a and PAG oil canbe used in the system.

• Re-affirm that a slight drop off inperformance could be experienced compared with pre-retrofit.

• Outline warranty coverage.

14

FURTHER

RETROFITTING

REQUIRED

Equipment

Page 70

Charging Stations


INDEX

Strain Gauge (by volume)

Dial-a-Charge (by volume)

Recovery/Recycle Unit

R134a

Manifold

Gauge Set

Vacuum

Pump

Graduated

Cylinder

Strain Gauge

Scales

Vacuum

Pump

Display

Manifold

Gauge Set

Refrigerant

Cylinder

These are two methods of charging refrigerant into

an A/C system. They are:

By volume - using a graduated charging dial cylinder.

By weight - using electronic scales with LCD read

out.

Both methods work well, but because R134a is

charge sensitive and most A/C system filter

drier's have no sight glass. It is recommended to

charge the system to the manufactures

specification using electronic weighing scales. The

advantage of using electronic scales over a

dial -a - charge type is that most dial - a- charge

cylinders only hold 4400 grams max. (before being

refilled) which is enough for approximately five (5)

A/C system charges.

The electronic scale type uses a refrigerant

cylinder of up to 25 kilograms enabling 25 A/C

system charges to take place before changing over

the cylinder.

Electronic Scale Type Charge/Evacuation Station

The charging cylinder sits on a set of scientific

quality scales and as the refrigerant is metered into

the A/C system the weight of the charging cylinder

is reduced. This reduction reads out on an LCD

display panel.Caution:As these stations use scientific grade

scales, care must be taken placing cylinders

on the scales and also moving them around in

the workshop.

Equipment


INDEX

Combination Units

Page 71

R134a

High Side

Hand Valve

Low Side

Hand ValvePressure

Display

Weight/Time

Display

Buttons for

different

functions:

l Charging;

l Recovery;

l Recycle;

l Evacuation;

l Oil Inject.

Rather than have a unit that only charges and evacuates an A/C system, there are combinationunits that carry out all the necessary servicing functions. Operations are entered into an electronic key pad.

These include :

l Charging to the specified amount.

l Evacuating for any duration required

l Recovering the refrigerant

l Recycling the refrigerant

l Injecting the lubricant

All these functions can be programmed into theunit via a control panel. The unit will automaticallycarry out all the pre-selected operations.

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa

Equipment


INDEX

Gauges

With the introduction of R134a, most equipmentmanufactures have changed gauge faces to read ineither:

l BAR pressure units;

l KILOPASCALS ( kPa );

l KILOGRAM CENTIMETRE SQUARE(KG/CM2);

l 1 BAR = 100 kPa;

l 1 KG/CM2 = APPROX 100 kPa;

n R12 was mostly in pound per square inch. (P.S.I.)

ACME Thread

(Female)

Rubber

Nylon

ReinforcementACME Thread

(Male)

Rubber

Rubber

Reinforcement

R12 Gauge HoseR134a Gauge

Equipment


INDEX

Recovery & Recycling

Page 73

R134a

R134a is a non ozone depleting refrigerant butfrom a cost point of view and the fact that R134aadds slightly to the green house effect, it is stilladvisable that it be recovered and recycled.

Due to the fact that most R134a A/C systemshave no sight glass in the FDR, you may berequired to remove the refrigerant more often andcharge to the specified amount.

l

l

l

IMPORTANT NOTES

Use only a specified R134a Recovery or Recovery/Recycle machine for R134a refrigerant.

Change device filters when suggested by equipment manufacturer.

Ensure oil collected during recovery is replaced into the A/C system ( clean oil ).

R134a Charge Adaptor

(Low Side)

R134a Charge Adaptor

(High Side)

Equipment

Page 74

Vacuum Pump


INDEX

Positive Pressure

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

kPa

Negative

Pressure

Owing to the highly hydroscopic nature of theR134a lubricating oil (PAG), it is essential that adeep full vacuum is reached.

The vacuum pump must pull:

-100 kPa ( - 1 BAR or - 1 KG/CM2(14.7psi) )

Servicing the Vacuum Pump

Before commencing the evacuation, check the oillevel sight glass located on the vacuum pump.Refer to manufactures specifications for the correct oil level.

After approximately 17 evacuations, drain all theoil from the vacuum pump and replenish with newvacuum pump oil. Oil changing is required due tothe hygroscopic nature of vacuum pump oil.Pulling the A/C system into a vacuum boils off any moisture which in turn contaminates the vacuumpump oil.

Connection to

Manifold Set Centre

(Yellow Hose)

Drain Plug

Oil Level

Use 3GS

Vacuum

Pump Oil

Breathe Cap

Ensure Oil

Breathing

Hole Clear

l

Caution

Ensure only the recommended lubricating oil

is used. This is normally of 3GS Viscosity.

Low Side Gauge

Vacuum Pump

Servicing

Refrigerant Safety


INDEX

Page 75

As R134a has a very low boiling point, care must be

taken when it is being handled. The following

safety precautions must be followed:

l Always wear eye protection;

l Wear gloves;

l Don’t allow R134a to contact bare skin. (as

this causes frost bite);

l Do not heat containers of R134a;

l Provide adequate ventilation when charging

or recovering R134a, as it is heavier than air;

l Use care when hot water steam cleaning the

engine. Hot water on the air conditioning

pipes and tubes could create thermal

expansion of the refrigerant contained in

the system;

l Avoid breathing R134a vapour;

l Do not transfer refrigerant from cylinder to

cylinder using a pump without knowing when

then bottle being filled has reached 80 % of its

capacity, as the remaining 20 % is used for

thermal expansion.Do Not Transfer Refrigerant

Do Not Apply Steam Cleaning Directly Avoid Breathing Refrigerant

Eye Protection

Hand/Skin Protection

Do Not Heat Containers

Servicing

Page 76

Leak Detection


INDEX

Refrigerant leaks must be found and rectified, as alow refrigerant charge will cause system damage;

l Air and moisture can enter a system at the leak point and cause internal components to corrode.

l Compressor lubrication depends on refrigerant circulation.

l Refrigerant helps cool the compressor.

l

l

IMPORTANT NOTES

Wipe dirt etc. from the areas being inspected;

This also applies for all types of leak detecting.

Pressure

Relief Valve or

Fusible Pin

Front Seal

Joints

Pressure

Relief ValveJoints

Leak Detection Methods

Visual Leak Detection

When a refrigerant leak occurs, it is common forthe lubricating oil to escape along with the refrigerant. The presence of oil and encrusteddust around hose fittings, joints and componentswill indicate a leakage point.

Joints

Servicing


INDEX

Leak Detection & Detectors

Page 77

5mm

Soap Solution

A mixture of dish washing liquid and water appliedaround the A/C system pipes and fittings will formbubbles at the leakage points.

Electronic Leak Detector

These leak detectors operate in various ways, themost common being that when the unit is turnedon, a low ticking sound can be heard and once theprobe locates a leak, the ticking sound increases toa high pitched noise. This can be achieved by moving the sensing tip slowly around the underside of components and fittings at a distanceof approximately 5mm. DO NOT allow the sensingtip to contact components or fittings as false readings and tip damage will occur.

l

l

l

l

l

l

l

IMPORTANT NOTES

Only use a detector designed to sense the refrigerant in the A/C system you are testing;Always clean dirt and grime from the section you are testing otherwise the sensing tip will be clogged;Regularly check the detectors sensitivity by sampling a small leak of refrigerant from a charging port shrader valve;Never allow the tip to contact the component being checked;Always check under fittings or components as refrigerant is heavier than air;Check for refrigerant leaks out of the wind;

Check for refrigerant leaks with engine stopped.

Servicing

Page 78

Leak Detection & Detectors


INDEX

Ultraviolet Fluorescent System

A fluorescent coloured dye is injected into theA/C system and allowed to circulate, then a specially designed ultraviolet lamp is passed overeach component in the A/C system. If a leak is evident, the coloured dye glows bright. Thismethod is exceptionally good for pin pointing asmall leak.

l

l

IMPORTANT NOTES

Check with the A/C system manufacturer to see if these dyes are suitable, and will not damage the A/C system components, such as the filter drier receiver (FDR) desiccant. Failure to do so could void the manufactures warranty.

Always check manufacturers recommendations, prior to using this methods.

l

l

l

IMPORTANT NOTES

Use the recommended dye for the refrigerant used in the A/C system;

The only fluorescent dye recommended by ‘Sanden’ is the ‘Iglo’ brand;

Always check manufactures recommendations, prior to using this method.

Refrigerant Dye

Normally red in colour, this dye is injected into theA/C system via the charging port. The A/C systemis then operated, if a leak is present, this red dyewill emerge and show as a stain around the fittingor component. This method is also good for pin pointing a small leak but leaves a heavy residue inthe A/C system

It is advisable to ask the customer to return inapproximately one weeks time as the dye couldtake longer to emerge if the A/C system has asmall leak.

Dye Injector

Page 79

Servicing

Lubrication


INDEX

Component Replacement

When replacing components, check the manufacturers recommendations on the quantityof oil to be added to the new component before installation. This is normally found in the particularvehicles workshop manual.

EXAMPLES of approximate quantities:

l Evaporator - 40cc

l Filter drier - 25cc

l Condenser - 30cc

l Accumulator - 40cc

l Evaporator - 40cc

l Hose blown - 50cc

l Tubes - 20 cc

Compressor (New Replacement)

Drain and measure the lubricating oil fromremoved compressor. Likewise, remove the oilfrom the new compressor, refill this new compressor with the same quantity of oil drainedfrom the old compressor. Use the new clean oilremoved from the new compressor plus 10cc toallow for any internal oil coverage.

E.G. 100cc

Removed

New Compressor

100 + 10cc =

110cc

New Compressor

Receiver Drier

Removed Compressor

Compressor

Hoses

Condenser

Faulty Compressor

Servicing

Page 80

Lubricating Oil


INDEX

VAC

UU

MOil Injector

Lubricating oil can be added to a non opened A/Csystem by using an oil injector.

Fill injector container to the required oil level.

Pull the A/C system into a deep vacuum, attach theoil injector hose to the low side charging port,open the oil injector valve and allow the vacuumcreated in the A/C system to pull the lubricating oilinto the low side of the A/C system.

l

l

l

IMPORTANT NOTES

Ensure only PAG oil is used with R134a refrigerant;

Min vacuum - 100kpa;

Use only specified PAG oil to suit the compressor..

Page 81

Servicing

Flushing a Contaminated System (as per SAE 1661 Standards)


CONDENSER

SELF MADE FITTING

FLUSH GUN

FLUSH, THEN REVERSE FLUSH

RECOVERY DEVICE

INVERTED DECANTING CYLINDER (LIQUID)

I f a seized or damaged compressor is to bereplaced, inspecting of the discharge hose interioris advised.

On inspecting the interior of the discharge hose, if particles or slivers of aluminium are found, flush-ing of the A/C system is required including a newfilter drier.

We recommend flushing individual components orsystem sections with refrigerant R134a, this refrigerant should be collected via a recovering

machine and can be used again. Component ortube connections (mostly self-made), will have tobe used and flushing carried out with the refrigerant in liquid form ie. the decanting cylinderturned upside down (inverted).

l

IMPORTANT NOTES

Failure to flush a contaminated system will lead to blockages in the condenser filter drier or

TX valve, and possibly cause compressor damage.

Servicing

Page 82

Preparation


INDEX

Fan Speed on High

Correct Belt Tension

Damaged or Blocked Fittings

Engine not Overheating

Dash Vents Fully Open

Drain Hose Blocked

Hoses Damaged

Damaged or Blocked FinsBefore servicing or diagnosing an A/C systemthere are preliminary checks that should takeplace.

These include :

l Checking for visual hose damage and chaffing.

l Ensure the condenser cooling fins are not blocked with obstructions such as insects, and the fins are straight.

l Condenser fan operates and runs in correct direction;

l Engine/radiator not over heating.

l Inspect drive belts for correct tension and damage.

l Engine viscous fan locks in at the correct temperature.

l Compressor cycles on and off.

l Evaporator drain hoses not blocked.

l Heater turned off in the full cold mode position.

l Air mix door fully closed.

l A/C switch illuminates when activated.

l No vacuum hose leakage.

l Dash vents open and close fully.

l No air leaks between evaporator case and heater case.

l Blower fan has all speeds operational.

l Any evidence of refrigerant leakage and oil staining at components or connections.

Page 83

Servicing

Pressure Gauges


INDEX

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

kPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

kPa

Introduction

An accurate diagnosis and determination of air conditioning system function and, moreimportantly, malfunction, depend largely upon theability of the technician to interpret gauge pressurereading. The importance of a refrigeration technicians manifold and gauge set is often compared to that of a physician’s stethoscope.

An improper gauge reading will relate to a specific problem. More than one problem may beassociated with a particular gauge reading, however. A system operating normally will have alow-side gauge pressure reading that correspondswith the temperature of the liquid refrigerant as itbecomes a vapour while removing heat from theair flowing over the evaporator coil surface. The high-side gauge readings should correspond withthe temperature of the refrigerant vapour as itbecomes a liquid while giving up its heat to theambient air flowing through the condenser.

Any deviation from ambient dependant normalgauge readings, other than slight, indicates a malfunction. This malfunction, if within the system,may be caused by a faulty control device, a restriction, or a defective component. It should benoted that improper mounting or location of components in a newly installed system may affectsystem performance. The vehicles engine may alsoaffect system performance and will be noted asabnormal gauge readings.

Pressure Gauge Pre Check

Always inspect pressure gauges to ensure the needles rest as zero on both low and high sides, ifthe needles(s) do not rest on zero, remove thehoses, open both taps, detach the dial face and gently turn the adjusting screw until the needle(s)rest on zero. Reconnect hoses and close taps.

Adjusting

Screws

Servicing

Page 84

Evacuation & Charging Procedure


INDEX

R134a

Performance Testing (General)

STEP 1. Park vehicle in a shaded area. Take noteof ambient temperature.

STEP 2. Open both front windows and enginehood.

STEP 3. Connect both high and low pressure service hose coupling valves to the system filling ports.

STEP 4. Open all dash louvers and adjust tothe straight ahead position.

STEP 5. Insert thermometer probe approximately 50mm into the centre vent louvre.

STEP 6. Set the controls to:A. Fresh air position;B. Maximum cooling;C. A/C on;D Highest blower speed.

STEP 7. Start engine, bring engine speed to 1700 RPM then allow pressure gauge needles to stabilise.

STEP 8. Take pressure and temperature readings. Compare these to the manufacturers performance charts found in appropriate workshop manuals.

NOTE: Only take pressure and temperature readings when the compressor is engaged.

As you can see from the above typica l performance test, the A/C system is put under anincreased load such as doors and engine hoodopen and high blower speed. If an A/C system can perform to the manufacturers specifications underthese loads, in normal driving situations withengine hood, windows closed and possibly a lowerblower speed, centre vent temperatures will bemuch lower.

Page 85

Servicing

Performance Chart Example


INDEX

Example

3.4

3.2

3.0

2.8

2.6

2.4

2.2

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.015 17 19 21 23 25 27 29 31 33 35

Suction Pressure Vs Ambient Temperature

Ambient Temperature (oC)

Su

cti

on

Pre

ssu

re (

kg

/cm

2)

RH:80%

RH:30%

22

20

18

16

14

12

10

8

6

4

2

015 17 19 21 23 25 27 29 31 33 35

Suction Pressure Vs Ambient Temperature

Ambient Temperature (oC)

FA

CE

AIR

OU

TL

ET

TE

MP

ER

AT

UR

E (

oC

)

RH:30%

RH:80%

Ambient Temperature = 25° C

Pressure = 1.8KG/cm2

Centre Vent = 4°C

Servicing

Page 86

Thermistor & Amplifier Testing (Electronic Compressor Clutch Cycling Control)


INDEX

8

7

6

5

4

3

2

1

0

0 5 10 15 20 25 30 35 40

Temperature (Co)

Resis

tan

ce

KΩ

Thermistor Testing

1. Disconnect the thermistor electrical plug.2. Measure the resistance between the two

terminals in the thermistor electrical plug.3. Consult the graph and compare the resistance

value eg.

Evaporator temperature 25°C. Thermistor resistance should be 2KΩ (2000 ohms)

Amplifier Testing

All amplifiers are sealed electronic units and cannot be tested. The only testing that can be performed is power/signals going to and from theamplifier. A workshop manual with wiring diagrams is required for this testing.

Amplifier

Page 87

Servicing

ECC (Electronic Climate Control) - Diagnostic Testing Example


INDEX

OFF

AMB

+

AMB

AMB

AMB

AMB

AMB

PRESS

LCD

Display

Readout

ALL LCD

Auto

Manual

A/C

Sensor

Inputs

Solenoids

Relay

and

Circuit

Operation

Fan

and

Step

Speeds

Air Mix Motor

and

PBR Feedback

Buttons

LowerDisplay Blue Button

Sub Stage Test

Red Button

Red Button to Step up through Fan Speeds

Main Display

Operating Fresh/Recirc

Motor

Stationary

Motor Runs

to Hot Position

Motor Runs

to Cold Position

Confirm Motor Operation - Inspect for Gear Movement

Requires Conversion to 0° to 60° Range for Air Mix Flap Position

Off

0

0

On

1

Off

0

On

1

Off

0

On

1

Off

0

On

1

Off

0

On

1

Off

0

On

1

Demist Foot Face Vent A/C Relay Water Tap

Solenoid

Relay State

Large

Display

Large

Display

Motor

State

Large

Display

Speeds

Test SensorAmbient

TemperatureSensor

° C-30 to +55

° C-30 to +55

° C-30 to +55

%0 to 99

%0 to 99

0 to 99 99 0

%0 to 50

%0 to 99

%0 to 99

In CarTemperature

Sensor

IntakeTemperature

Sensor

EvaporatorTemperature

Sensor

WaterTemperature

Sensor

SunLoad

Sensor

PBRFeedback

Sensor

Air MixMotorSupply

Large DisplayRange

Display 1 Display 1 Display 2 Display 1,2 Display 3

All of the Screen Segements, Numerics and Icons Displayed

Display 1,3 Display 1,2,3 Display A

Components

and

Circuits

in Test

1 2 3 4 5 6 7 8 9 10 12 13

4 4 = Sensor in Range8 8 = Sensor Open or Short Circuited

Confirm Operationof Circuit

i.e. Air FlowWater FlowClutch Engagement

Servicing

Page 88

Diagnosis for A/C Systems


INDEX

This test is designed for typical workshop conditions:

l 21 -37°C;l Various Humidities and Sun Load.

Follow the chart exactly to create enough cooling load to causethe V5 compressor to operate at full stroke. Accurate resultswill not be achieved otherwise

Neutralise internal vehicle temperature to workshop ambientconditions, insert thermometer into centre duct.

l Hood Up; l Open doors/windows;l Temperature lever at full cold;l Normal A/C mode; l Hi blower speed;l Engine at fast idle (1500 rpm).

Condenser fan runs during all A/C modes.

Condenser fan does not run in

A/C modes.

Close doors/windows. Set A/C controls to:

l Normal A/C Mode;l High Blower Speed;l Temperature lever at full cold;l Normal A/C mode;

Run engine at idle for five minutes.

Reference cooling fan diagnosis section of

service instructions

Record:

l High and low side pressures after A/C system has been operating for five minutes;

l Centre outlet duct temperature.

Variable Stroke Harrison V5 Compressor

Page 89

Servicing

Diagnosis for A/C Systems


INDEX

550

F

400

E

280 C

D

A

140 B

700 1400 2100 2700

HIGH SIDE PRESSURE (kPa)

Variable Stroke Harrison V5 Compressor

Diagnostic Chart

1. Use the following chart which corresponds to the present ambient temperature.

2. Read the high and low side pressure and notethe letter coded area in which they intersect.

3. Match the letter code with the corresponding code in the diagnostic chart.

A. Normal system;B. Low refrigerant;C. Refrigerant overcharge or receiver/dryer

restricted;D. TXV closed;E. TXV stuck open;F. Compressor not pumping.

Ambient - 32°C;

Low Pressure - 200 kPa;

High Pressure - 1400 kPa;

= Grid A (Refrigerant system normal)

LO

WS

IDE

PR

ES

SU

RE

(kP

A)

550

F

400

E

280 D C

140 B A

700 1400 2100 2700


LO

WS

IDE

PR

ES

SU

RE

(kP

A)

LO

WS

IDE

PR

ES

SU

RE

(kP

A)

LO

WS

IDE

PR

ES

SU

RE

(kP

A)

550

F

400

E

280 D C

140 B A

700 1400 2100 2700


550

F

400

E

280 D A C

140 B A

700 1400 2100 2700


EXAMPLE

Example

Ambient 21°C Ambient 26.5°C

Ambient 37.5°CAmbient 32°C

Servicing

Page 90

TX Valve Diagnosis


INDEX

If when carrying out pressure gauge diagnosis it isfound the TX valve is at fault, ie.

Jammed fully open - high/low pressure too high,

OR

Jammed fully closed - low pressure zero to a vacuum;

then follow the testing procedure below.

Testing

a. Remove the evaporator case and dismantle;

b. Detach the TX valve pressure compensatingtube and temperature sensing bulb from the evaporator outlet side; Mark the area on the outlet tube where the sensing bulb is clamped when replacing a TXvalve. This sensing bulb must be fitted in exactly the same position.

Opening Test: warm the temperature sensingbulb by hand, the TX valve shouldnow be fully open. This can be verified by blowing through thevalve.

Closing Test: into a container of water andcrushed ice, place the temperaturesensing bulb and gently stir, the TXvalve should now be fully closed.This can be verified by blowingthrough the valve.

If any of the above tests fail, replace the TX valvewith the correct type ie (tonnage and super heat).Ensure new ‘O’ rings are used and that the temperature bulb is in direct contact with the evaporator outlet tube and that the bulb is covered with insulating material to ensure no false temperature readings are obtained.

Caution - when bending the temperature sensing tube to fit, care must be takennot to break it as this tube is hollowand contains refrigerant.

Opening Test

Closing Test

Water and

Crushed Ice

Page 91

Servicing

Pressure Switch Electrical Test


INDEX

When tracing a fault in the A/C circuit, alwayscheck for power at both sides of possible pressureswitch terminals with a multimeter. If the pressureswitch is deactivated this could indicate a refrigerant over or under charge.

Thermostat

A/C Switch

Compressor

Clutch

Low Pressure

Switch

Medium

Pressure

Switch

High Pressure

Switch

Servicing

Page 92



INDEX

C E F G

A B

D

H

LOW HIGH

REFRIGERANT

RECOVERY

UNIT VACUUM

PUMP

ΣΠΕΧΙΦΙΕ∆ ΧΗΑΡΓΕ _ _ _ _+/−_ _ _ _ ΓΡΑΜΣ

NOTE: 1. Gloves and safety glasses

must be warn.

2. Work in a well ventilated

area.

3. Do not smoke near

refrigerant.

4. Avoid PAG oil contacting

paint work. Wash off

immediately.

Start vacuum pump, open valve F,

open valves A & C low pressure

filling hose.

High side

gauge reads

below zero

High side

gauge not

below zero

Blockage or leak

evident in system.

find cause and

rectify.

Leave valves A, C, & F open. Slowly

open high side valves B & D.

Evacuate system to 6 kpa

absolute.

Close valves A, B & F.

System must maintain 6 kpa

-absolute for a minimum

of 15 mins.

Low pressure gauge

needle steady

Recover refrigerant from

system, open valves A, B, C,

D, E and H. After the recovery

procedure close valve E. Open

valve F and continue the evacuation

procedure for a minimum of 15 mins

then close valves A, B & F. Turn

pump off. (Refer Fig. 1)

Low pressure gauge

needle rises.

Continue evacuation

for 15 mins.

Partially charge system

with 200 grams of

refrigerant

Partially charge system with

200 grams of refrigerant

through high filling hose.

Locate leakage using an

electrical leak detector.

Check on the underside of

all fittings and components

Recover refrigerant from

system open valves A, B, C,

D, E, & H. (Refer Fig. 1)

Repair leak source

Continue with evacuation

and charging procedure

as per steps 1-3

NOTE: Indicates stop tap or valve-fit these

whenever a hose has to be removed

Fig. 1

Check for leakage using

an electronic leak

detector

STEP 1

EVACUATION

STEP 2

LEAK TESTING

Page 93

Servicing



INDEX

C E F G

A B

D

H

LOW HIGH

REFRIGERANT

RECOVERY

UNIT VACUUM

PUMP

C

A B

D

H

LOW HIGH

REFRIGERANT

RECOVERY

UNIT

First Aid: In the event of R134a contacting the

eye, carry out the folllowing procedure:-

1. Do not rub eye

2. Splash large quantities of water into the eye to

raise the temperature.

3. Continue to irrigate the eye for 15-20 mins.

4. Take patient without delay to hospital or

physician.

5. Do not attempt to treat yourself.

Start engine set to fast idle.

Activate A/C switch. Set

controls to maximum cooling

and high fan speed.

Open low side valves, A & C

slowly and complete the

charging process (If required).

Caution: do not allow more than

275 kpa to register on the low

side gauge during charging.

Close all valves and taps.

Remove high and low filling hoses,

make sure valves C & D are closed.

Connect high side filling hose to

recovery unit inlet side. Open valves

A, B & D. Switch on recovery machine

and remove all refrigerant in filling

hoses. (Refer Fig. 3)

Carry out performance testing.

Refer appropriate workshop

manual for specifications.

Fig. 3

Fig. 2

Warning: Never run compressor

without refrigerant in

system as the compressor

relies on refrigerant/oil flow.

Any oil displaced during the

refrigerant recovery process

must be replaced in the

system before charging can

commence. The R134a

system uses P.A.G. (poly-

alkylen glycol) lubricating

oil. Use specified oil type.

Warning: Never charge system

through the high side

with the compressor

running.

Open high side valves B, D & G.

Without exceeding the

specified amount,

allow as much refrigerant as

possible to enter system

Close valves B & D. rotate

compressor front plate 12

revolutions to ensure no

liquid is trapped in the

compressor.

STEP 3

CHARGING

SYSTEM

INDEX

ΠΡΟΒΛΕΜ ΧΟΝ∆ΙΤΙΟΝ ΧΑΥΣΕ

Servicing


1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa

Εξχεσσιϖε αιρ

(Νον Χονδενσαβλεσ)

(ΧΧΤΞς/ΧΧΟΤ Σψστεµ)

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa

Λοω Σιδε Γαυγε − Ηιγηερ ορ λοωερ τηαν χοντρολποιντ πρεσσυρε;Ηιγη Σιδε Γαυγε − Νορµαλ;∆ισχηαργε Αιρ − Χοολ ονλψ ιφ αβοϖε χοντρολποιντ;Εϖαπορατορ − Φρεεζεσ υπ ιφ τοο φαρ βελοωχοντρολ ποιντ;Νοτε −Ρεφερ το αππροπριατε ωορκσηοπ µανυαλ φορ λοωσιδε χοντρολ ποιντ πρεσσυρε.

l Χοµπρεσσορ χοντρολϖαλϖε φαυλτψ ορ ινχορρεχτϖαλϖε ρατινγ υσεδ. Τηεσεϖαλϖεσ αρε σταµπεδ ωιτηα λεττερ χοδε ον τηεϖαλϖε βοδψ ινδιχατινγτηε πρεσσυρε χοντρολποιντ φορ τηε λοω σιδε οφτηε σψστεµ.εγ. Χοδε Ψ∏Ψ=290κΠΑ (αβσολυτε) =160−200κΠΑ.(Λοω γαυγε ρεαδινγ)Νοτε −Ρεφερ αππροπριατε ωορκσηοπ µανυαλ.

Χοµπρεσσορ Χοντρολ ςαλϖε

Μαλφυνχτιον

(Ηαρρισον ς5 ςαριαβλε

Στροκε Χοµπρεσσορ)

Λοω Σιδε Γαυγε −

Ηιγη;

Ηιγη Σιδε Γαυγε −

Λοω;

Χοµπρεσσορ −

Νοισψ;

∆ισχηαργε Αιρ −

Ωαρµ;

∆ισχηαργε Ηοσε −

Χοολ.

l Χοµπρεσσορ φαυλτψ,

ιντερναλ φαιλυρε;

l Βλοχκαγε ιν συχτιον

ηοσε αφτερ τηε λοω σιδε

φιλλινγ πορτ;

l ΧΧΟΤ σψστεµ − βλοχκεδ

αχχυµυλατορ.

Χοµπρεσσορ Μαλφυνχτιον



Ηιγη;


Ηιγη;


Σλιγητλψ Χοολ;

Νοτε −

Λοω Σιδε Πρεσσυρε Γαυγε

νεεδλε δοεσ νοτ φλυχτυατε

ωηεν χοµπρεσσορ χψχλεσ

Ον ανδ Οφφ.

l Λαργε αµουντσ οφ αιρ

ανδ µοιστυρε ιν σψστεµ

χαυσεδ βψ ινσυφφιχιεντ

εϖαχυατιον τιµε ορ νο

εϖαχυατιον αφτερ

ρεπαιρινγ ορ σερϖιχινγ

τηε σψστεµ;

l Λεακινγ χοµπονεντσ

ωιτηιν τηε σψστεµ

αλλοωινγ µοιστυρε ανδ

αιρ το εντερ.

INDEXServicing



1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa


Λοω το ςαχυυµ;


Λοω;


Σλιγητλψ Χοολ;

Οριφιχε Τυβε −

Φροστ βυιλδ υπ;

Λοω Πρεσσυρε Σωιτχη −

∆εαχτιϖατεδ.

l Οριφιχε τυβε φιλτερ σχρεεν

βλοχκεδ ωιτη δεβρισ

συχη ασ αλυµινιυµ

παρτιχλεσ.

Οριφιχε Τυβε Βλοχκεδ

(ΧΧΟΤ Σψστεµ)


Λοω το ςαχυυµ;


Λοω;


Σλιγητλψ χοολ;

Εξπανσιον ςαλϖε −

Σωεατινγ ορ Φροστ βυιλδ υπ.

l Εξπανσιον ϖαλϖε (ΤΞ)

ϕαµµεδ χλοσεδ,

ινσυφφιχιεντ ρεφριγεραντ

φλοω το συχτιον σιδε οφ

τηε χοµπρεσσορ.

Τηισ ισ νορµαλλψ ρελατεδ

το τηε ΤΞς σενσινγ βυλβ

µαλφυνχτιον,

δισχοννεχτεδ φροµ

τυβε, φορειγν µατεριαλ ιν

ΤΞς

ορ

µοιστυρε εντρψ χαυσινγ

ρυστ φορµατιονσ.

Εξπανσιον ςαλϖε (ΤΞ)

ρεµαινσ χλοσεδ

(ΧΧΤΞς σψστεµ)

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa


Ηιγη;


Ηιγη;


Ωαρµ;

Συχτιον (λοω) Σιδε Ηοσε −

Σωεατινγ ορ Φροστ βυιλδ υπ.

l Εξπανσιον ϖαλϖε (ΤΞ)

ϕαµµεδ οπεν ανδ νοτ

µοδυλατινγ, χαυσινγ

φλοοδινγ οφ εϖαπορατορ

ωιτη ρεφριγεραντ.

Τηισ ισ νορµαλλψ ρελατεδ

το ινχορρεχτ ποσιτιονινγ

οφ τεµπερατυρε σενσινγ

βυλβ ορ φορειγν µατεριαλ

ανδ µοιστυρε εντρψ

χαυσινγ ρυστ φορµατιονσ.Εξπανσιον ςαλϖε (ΤΞ)

ρεµαινσ οπεν

(ΧΧΤΞς σψστεµ)

INDEXServicing



1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa


Λοω το Νορµαλ;


Ηιγη;


Ωαρµ;

Ηιγη Σιδε Τυβεσ −

ςερψ Ηοτ;

Χοµπρεσσορ Χλυτχη − Χουλδ

χοντινυαλλψ χψχλε ον τηε

ηιγη πρεσσυρε σωιτχη.

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa


Ηιγη;


Ηιγη;

Αφτερ Οριφιχε Τυβε −

Ωαρµ;

Αχχυµυλατορ −

Ωαρµ.

l Φαυλτψ τηερµοστατιχ

σωιτχη.

Οριφιχε Τυβε Βψπασσ

(ΧΧΟΤ Σψστεµ)

l Ρεφριγεραντ οϖερχηαργε;

l Ενγινε ορ χονδενσερ

φαν νοτ οπερατινγ;

l Χονδενσερ φινσ χλογγεδ

ωιτη δεβρισ;

l Νο σεαλινγ φοαµ

βετωεεν χονδενσερ &

ραδιατορ;

l Οβστρυχτιον ιν φροντ οφ

χονδενσερ εγ. βυλλ βαρ,

ινσεχτ σχρεεν;

l Φαν βελτ σλιππαγε;

l Ραδιατορ οϖερ ηεατινγ.

Χονδενσερ Μαλφυνχτιον

ορ Οϖερχηαργε



Λοω το Νορµαλ;


Νορµαλ;


ςερψ χολδ τηεν γοεσ ωαρµ;

Εϖαπορατορ −

Φρεεζεσ υπ;

Αιρ Φλοω −

Ρεστριχτεδ ωηεν

εϖαπορατορ φρεεζεσ υπ ορ;

χοµπρεσσορ χψχλεσ Ον ανδ

Οφφ τοο φαστ.

l Ρεφριγεραντ βψ−πασσινγ

τηε οριφιχε τυβε.

l Ο∏ ρινγσ ον οριφιχε τυβε

δαµαγεδ ορ µισσινγ;

Τεµπερατυρε Χοντρολ

Σωιτχη

(δε−ιχινγ χοντρολ)

(ΧΧΤΞς Σψστεµ)

Servicing


PROBLEM CONDITION CAUSE

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa

1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa

Refrigerant Loss

(CCOT System)

Electrical Fault

(CCTX/CCOT System)

Restriction in High Side

of System

(CCTX/CCOT System)

Low Side Gauge -

Low;

High Side Gauge -

Low;

Discharge Air -

Cool;

Accumulator -

Warm;

Low Side Gauge -

High;

High Side Gauge -

Low;

Discharge Air -

Warm;

Compressor -

Not operating;

Note -

Both high and low pressure

readings will be the same

Low Side Gauge -

Low;

High Side Gauge -

Low;

Discharge Air -

Slightly Cool;

High Side Tubes -

Cool and showing signs of

sweating or moist build up

ot the point after the point

of restriction;

l Refrigerant leak from

system or normal

refrigerant loss over a

period of years in

operation.

l Refrigerant undercharge

l Electrical component

open circuit;

l Thermostat;

l Pressure switch;

l Clutch coil;

l Fuse;

l A/C switch;

l Blown switch;

l Wiring;

l No power to compressor

clutch system. Not

operating pressure

normally. Equal appr. 500-

600 kpa high & low side

l Foreign material causing

blockage between the

compressor outlet and

evaporator inlet

(high side) l No or very little refriger-

ant flow to suction (low)

side of compressor.

Note - Compressor - Noisy,

fast cycling depending if

the high pressure switch

is before or after the

restriction.

INDEXServicing



1

0

1

2

3 45

6

7

8

-100

0

100

200

300400

500

600

700

800

LOW

BAR

KPa

5

10

15 20

25

30

350

500

1000

1500 2000

3500

2500

3000

HIGH

BAR

KPa


Νορµαλ το ςαχυυµ;


Νορµαλ;


Βεχοµεσ ωαρµερ ασ τηε

λοω σιδε χψχλεσ το α

ϖαχυυµ;

Συχτιον (λοω) Σιδε Ηοσε −

Ωιλλ φροστ ιν τηε χασε οφ α

ΧΧΟΤ σψστεµ.

εγ. αχχυµυλατορ.Εξχεσσιϖε Μοιστυρε


l Μοιστυρε χαν φρεεζε

ωιτηιν τηε εξπανσιον

ϖαλϖε ανδ χαυσε

βλοχκαγεσ τηρουγη ρυστ

φορµατιον

INDEX

Page 99

Servicing

Diagnostic Tips


Blockage - A/C System

A very useful diagnostic aid is the ‘Feel Test’. As thetest implies it is a matter of quite simply feelingtubes and components for temperature drops,indicating possible blockage location.

By this stage you would be aware of what side ofthe A/C system should be hot and what sideshould be cold. But what also happens with thepressure gauge reading, sometimes they don’tmake sense.

Normal System

l High side - Hot;

l Low side - Cold

Indicates Blockage.

Blockage - High Side (after charge port)

l High side pressure - High;

l Low side pressure - Low to normal;

l High pressure switch will not deactivate the

A/C system, low pressure switch might;

l Compressor noisy;

l High side hose very hot before blockage;

l High side hose very cool to warm after

blockage.

The location of the charging ports in relation tothe A/C system must be taken into consideration.A pressure gauge reading could be high or lowdepending on what side of the charge port theblockage is located. Use the ‘Feel Test’ as well as thepressure gauge readings.

INDEX

Servicing

Page 100

Diagnostic Tips


Blockage - High Side (before charge port)

l High side pressure - Low;

l Low side pressure - Low to normal;

l High pressure switch will not deactivate the

A/C system, low pressure switch might;

l Compressor noisy;

l High side hose very hot before blockage;

l High side hose very cool to warm after

blockage.

Blockage - Low Side (after charge port)


l Low side pressure - High;

l Low pressure switch will deactivate the A/C

system;

l Frosting of the low side hose/fittings before

the blockage.

Blockage - Low Side (before charge port)


l Low side pressure - Low to vacuum;


system;

l Frosting of the low side hose/fittings before

the blockage.

Frosted

Hose

Frosted

Hose

INDEX

Page 101

Servicing

Diagnostic Tips


Low

Warm

Warm

Cool

Cool

Lowto

Zero

Blockage - Orifice Tube (CCOT system)


l Low side pressure - Low to vacuum;


system;

l Frosting of the tube after the orifice tube.

Blockage - Receiver Drier

l High side pressure - High;

l Low side pressure - Low to Vacuum;

l Low pressure switch should deactivate the

A/C system;

l If the blockage is in the receiver drier itself,

the outlet tube will be frosted.

Checking refrigerant charge - CCOT system

Run the A/C system, place one hand at the outlet

side of the orifice tube and one hand on top of the

accumulator.

If the temperature of the accumulator is higher

than the temperature after the orifice tube, then

the refrigerant charge is not to specification. Add

150gms and recheck.

Frosted

Tube

Frosted

Tube

Orifice

Tube

Orifice

Tube

INDEXServicing

Page 102

Diagnostic Tips


Blockage - Condenser

A change of state, where high pressure vapourforms into a high pressure liquid during the movement through the condenser, takes placewithin approximately the first 1/3 of the condenser. With this change of state a slight(depending on ambient temperature) temperaturechange takes place.

Using your finger, follow the tube(s) of the condenser (avoid burning your skin), you can feelwhere the change of state takes place. This changewill however be quite subtle. But if you feel thedifference in temperature before approximatelythe first 1/3 , a blockage maybe present.

With the parallel flow design condenser, refrigerant flows through more than one tube sothe possibility exists that the condenser will operate sufficiently in lower ambient. But when theambience increases and greater refrigerant flow isrequired, a blockage in one tube will cause problems such as poor performance and excessivedischarge pressures.

High

Pressure

Liquid

High

Pressure

Vapour

High

Pressure

Liquid

High

Pressure

Vapour

Indicates Blockage

Indicates Blockage

Documents

30383473 Automotive Aircnditioning Training Manual