Troubleshoot Air Conditioning

7/30/2019 Troubleshoot Air Conditioning

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Troubleshoot Air Conditioning

Copyright AA1Car

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A/C COOLING PROBLEM?

The most likely cause of an automotive air conditioner cooling problem is no refrigerant in the system. Ifthe refrigerant has escaped past a leaky compressor or O-ring seal, leaked out of a pinhole in theevaporator or condenser, or seeped out through a leaky hose, the leak needs to be identified andrepaired before the system is recharged.

On many systems, the compressor will not turn on if the refrigerant is low because the "low pressuresafety switch" prevents the compressor clutch from engaging if system pressure is low. This protects the

compressor from possible damage caused by a lack of lubrication.

One of the first things you should check, therefore, is compressor engagement. If the compressorsmagnetic clutch is not engaging when the A/C is turned on, the problem may be a blown fuse or a wiringproblem. If the fuse is blown, replacing it may restore cooling temporarily. But the underlying reason forthe fuse blowing in the first place needs to be identified and corrected to prevent the same thing fromhappening again.

If the magnetic clutch is receiving voltage but is not engaging the compressor, the clutch is defective andneeds to be replaced. If there is any evidence of leakage around the compressor shaft seal, the sealshould also be replaced.

If the clutch works but fails to turn the compressor (the belt may squeal in protest!), the compressor has

seized and needs to be replaced.

Compressor failures are usually the result of loss of lubrication, which in turn may be due to lowrefrigerant in the system, a blockage (such as a plugged orifice tube which prevents refrigerant and oilfrom circulating to the compressor), loss of lubricant due to leaks or improper service procedures (notadding oil to the system to compensate for oil lost through leakage or component replacement), or use ofthe wrong type of lubricant.


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R-12 systems require mineral oil while R-134a systems require various types ofPAG oilor POE oil. Usingmineral oil in a newer R-134a system can cause serious lubrication problems as can using the wronggrade (viscosity) of PAG oil. Always follow the vehicle or lubricant manufacturers compressor oilrecommendations.

The next thing you should check when troubleshooting a no cooling problem is system pressure. For this,

you need a set of A/C service gauges. Attach your service gauges to the high and low service fittings. Ifboth the high and low side pressure gauges read low, the system is low and needs recharging. But beforeany refrigerant is added, check for leaks to find out where the refrigerant is going.

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AIR CONDITIONING PROBLEM: REFRIGERANT LEAKS

All vehicles leak some refrigerant past seals and through microscopic pores in hoses. The older thevehicle, the higher the rate of seepage. Newer vehicles have better seals and barrier style hoses sotypically leak less than a few tenths of an ounce of refrigerant a year. But system capacities also tend tobe smaller on newer vehicles, so any loss of refrigerant will have more of an adverse effect on coolingperformance.

Various methods can be used to check for leaks. The telltale oil stainsand wet spots that indicate leakson older R-12 systems are less apparent on the newer R-134a systems because PAG lubricants are notas "oily" as mineral oil. This makes it harder to see leaks.

Leaks can be found by adding special dye to the system (available in pressurized cans premixed withrefrigerant), an electronic leak detector, or plain old soapy water (spray on hose connections and watchfor bubbles -- requires adding some refrigerant to system first and turning the A/C on). Once you've founda leak, repairs should be made prior to fully recharging the system. Most leak repairs involve replacing O-rings, seals or hoses. But if the evaporator or condenser are leaking, repairs can be expensive.
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POOR COOLING PERFORMANCE

Diagnosing an A/C cooling problem is best done by connecting a gauge set to the high and low pressureservice fitting on the system. Though poor cooling is often due to a low charge of refrigerant, it can alsobe caused by many other factors (see chart above).

How to tell if your A/C system needs refrigerant: look at the LOW pressure gauge reading whentheengineis OFF. On an 80 degree day, the LOW gauge should read about 56 psi or higher if the A/Csystem contains an adequate charge of refrigerant. On a 90 degree day, the LOW side reading should beabout 70 psi or higher. If the LOW gauge reading is less than this, the A/C system probably needs someadditional refrigerant.

Refer to the vehicle manufacturer specifications for normal system operating pressures, and the totalrefrigerant capacity of the system. Most newer passenger car A/C systems do not hold much refrigerant(14 to 28 oz.), so you don't want to add too much if the system is low.

AIR CONDITIONER PROBLEM: INTERMITTENT COOLING

An A/C system that blows cold air for awhile then warm air is probably freezing up. This can becaused by air and moisture in the system that allows ice to form and block the orifice tube.

Evacuating the system with avacuum pumpwill purge it of unwanted air and moisture. Evacuation shouldbe done with avacuumpump that is capable of achieving and holding a high vacuum (29 inches) for atleast 30 to 45 minutes.

For best performance, an A/C system should contain less than 2% air by weight. For every 1% increasein the amount of air that displaces refrigerant in the system, there will be a corresponding drop of aboutone degree in cooling performance. More than 6% air can cause a very noticeable drop in coolingperformance, and possibly cause evaporator freeze-up.
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Air can get inside a system through leaks, by not evacuating the system prior to recharging it, and/or byrecharging the system with refrigerant that is contaminated with air. Recovery equipment can suck air intothe recycling tank if an A/C system contains air or if the system has a leak. For this reason, the refrigerantrecovery tank on recycling equipment must be checked and purged daily. On some equipment, this isdone automatically. But on equipment that lacks anautomaticpurge cycle, tank pressure andtemperature has to be measured and compared to a static pressure reference chart.

Some refrigerant identifier equipment can detect air in the system as well as other contaminants. Anidentifier should be used to check the refrigerant before the system is serviced to prevent cross-contamination of recovery and recycling equipment.

Possible causes of intermittent cooling in a manual A/C system that might be caused by an electricalproblem include:

Faulty low pressure cutout switch. This switch prevents the compressor from running if the refrigerantlevel is low. If the cutout switch is not reading correctly, it can prevent the compressor from coming on.

Faulty compressor clutch. The magnetic clutch on the compressor requires full battery voltage to engage.If the voltage to the clutch is low, or the clutch coils have too much resistance, or the air gap in the clutch

is too great, the clutch may not engage to drive the compressor.

Faulty compressor clutch relay. Check to see if the relay is receiving voltage when the A/C is turned on.Also check the relay wiring and ground connections. If bypassing the relay with a jumper wire or routingbattery voltage directly to the compressor clutch makes the A/C work, the relay is probably bad.

Faulty A/C control switch. The switch may be worn and not making good contact when it is turned on.

Some possible causes of intermittent cooling (or no cooling) on automatic A/C systems include all of theabove, plus:

A problem in the control module or control head (this usually requires using a dealer scan tool to readfault codes and perform self-diagnostics).

A bad temperature sensor (an ambient air temperature sensor, interior air temperature sensor, evaporatortemperature sensor, or sunload sensor). Again, a factory scan tool is usually required to performdiagnostics on the system.

AIR CONDITIONING PROBLEM: NOISE

Noise from the compressor usually means the compressor is on its way out. But noise can also becaused by cross-contaminated refrigerant (operating pressure too high), air in the system or the wrongtype of compressor lubricant.

Noise can also be caused by hoses or other parts rattling against other components in the enginecompartment. Check the routing of the hoses, support brackets, etc., to pinpoint the noise.

TROUBLESHOOTING AIR CONDITIONING ODOR

If a vehicles air conditioner blows out air that smells like the inside of oldgymsneaker when the A/C isturned on, microbes are growing on the evaporator. Mold likes damp, dark places. Bacteria can alsothrive under such conditions. Besides smelling bad, it can be unhealthy to breathe (ever hear ofLegionnaires Disease?).
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To get rid of the unwanted organisms, various chemicals can be sprayed on the evaporator directly orthrough the blower ducts or air intake. Many replacement evaporators have a special chemical coatingthat inhibits the growth of mold and bacteria. The drainage tubes that carry condensation away from theevaporator should also be inspected and cleaned.

A/C FLUSHING

If the compressor has failed, or the system is full of sludge or contamination, the condenser, evaporatorand hoses should all be flushed with an approved flushing chemical (such as Dura 141b) to clean the A/Csystem. Flushing can help prevent repeat compressor failures and system blockages by dislodging andcleaningout sludge and debris. Replacing badly contaminated parts such as the condenser, accumulatoror receiver-drier and orifice tube or expansion valve is another way to get rid of these contaminants, butflushing is usually a more practical and economical choice. Regardless of which approach you use, theorifice tube or expansion valve should always be replaced when contamination is found.

NOTE: Some types of compressors can be very difficult to flush completely. These include "parallel" flowcondensers and those with extremely small passegeways. If contaminated, these types of condensersmust be replaced to reduce the risk of a repeat compressor failure. Installing an in-line filter is alsorecommended for added insurance,

When a compressor fails, a lot of metallic debris is often thrown into the system. Most of this debriscollects in the condenser where it can cause blockages that reduce cooling performance. If the debris iscarried through the condenser and enters the liquid line, it can plug the orifice tube or expansion valve.This can block the flow of refrigerant and lubricating oil causing a loss of cooling and possible compressordamage. Debris can also migrate backwards from the compressor through the suction hose causingblockages in the accumulator or receiver-drier.

Another source of trouble can be debris from old hoses that are deteriorating internally. Tiny flakes ofrubber can be carried along to the orifice tube or expansion valve and cause a blockage.

Sludge is usually the result of moisture-contamination. The blackish goo that results can damage thecompressor and plug the orifice tube or expansion valve. The moisture-absorbing "desiccant" in theaccumulator or receiver-drier is supposed to prevent this from happening. But the desiccant can only holdso much moisture. Once saturated, sludge begins to form. So you should also replace the accumulator orreceiver-drier if the system is contaminated, has leaks or must be opened up for repairs.

Another reason for flushing is to remove residual lubricating oil from the system. This should be donewhen retrofitting an R-12 system to R-134a. It should also be done if the lubricating oil is contaminated orthe system contains the wrong type of oil for the application. Flushing out the old oil can prevent oilovercharging, reduced cooling performance and/or lubrication incompatibility problems.

For added insurance after flushing, you can install a high side filter to protect the orifice tube or expansionvalve from any residual debris that might still be in the system, and/or a second filter in the suction hoseto protect the compressor.

R134A RETROFIT

As long as R-12 is available, there is no real reason to convert older vehicles to R-134a. That is becauseR-12 systems cool best when charged with R-12 refrigerant. But converting to R-134a does make senseif your A/C system requires major A/C repairs (such as a new compressor, condenser or evaporator). Theextra cost involved to make the changeover to R-134a does not add that much to the total repair bill.
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A basic retrofit procedure can be done one of two ways. The "Type 1" retrofit follows the OEMrecommended procedure and generally involves removing all the old mineral oil from the system,replacing the accumulator or receiver-drier with one that contains a desiccant (X-7) which is compatiblewith R-134a, replacing O-rings (if required), installing or replacing a high pressure cutout switch and/ororifice tube (if required), then adding the specified PAG oil and recharging the system with R-134a.Federal law also requires the installation of R-134a fittings on the high and low service ports to reduce thechance of refrigerant cross-contamination the next time the vehicle is serviced, and labels that identify thesystem has been converted to R-134a. For more information, see theR134A RETROFIT GUIDE programfeatured on this website.

Click on image for more info

A "Type 2" procedure is more of a "quick and cheap" approach to retrofit. On many 1989 through 1993vintage vehicles, the R-12 A/C systems can be converted to R-134a by simply recovering any of the R-12that is left in the system (NOTE: it is illegal to vent refrigerant into the atmosphere!), adding POE oil(which is compatible with both types of refrigerant), and then recharging with R-134a.

NOTE: Type 2 conversions cannot always be done on some vehicles because their compressors may notbe compatible with R-134a (any compressor with Viton seals has to be replaced). This includes originalequipment compressors such as Tecumseh HR980, some Keihin compressors and some Panasonicrotary valve style compressors in older Nissan vehicles.

Durability is another concern. Because R-134a raises compressor discharge pressures and increases thecompressors work load, some lightweight compressors may not be rugged enough to tolerate R-134aover the long haul. This applies to the Harrison DA6 and Ford FX-15 compressors. The Harrison DA6 canbe replaced with a HD-6, HR-6 or HR-6HE compressor. The Ford FX-15 compressor can be replacedwith a FS-10 compressor.Share
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How to Check Your Car's Air Conditioning SystemCopyright AA1Car

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You should check your car's A/C system BEFORE hot weather arrives to make sure it is working properlyand blowing cold air. The following tips on how to check your car's air conditioning systemhas beenprovided by theMobile Air Conditioning Society (MACS):

Note: Always be extremely careful any time you are under the hood while the engineis running. Stayaway from all rotating components with your hands, clothing, and hair, and always wear eye protectionaround a running engine.

1. With the engine running, does thecompressor clutchengage when the A/C is switched on? If itdoes not, this usually indicates a low (or empty) refrigerant condition, or an electrical problem. Also, listenfor rapid clicking orcyclingnoises at the compressor when the A/C is switched on. If this is happening, itcould also indicate low refrigerant or some other problems. Have it checked by your service technician.(Note: Some A/C systems prevent compressor clutch engagement in low temperatures, typically at orbelow 40 F.)

2. Is the A/C system blowing cold air? Luke warm air or air that is barely cooled at all could indicate alow refrigerant charge in the A/C system. Pressure gauges can be used to check the refrigerant charge. Iflow, add refrigerant to bring the system up to full charge. SeeHow To Recharge Your Car's AirConditionerfor more information on how to add refrigerant.

3. With the engine running and the A/C switched off, listen for knocking or rumbling sounds in thevicinity of the compressor. These could indicate a failing compressor clutch, and/or loose mountinghardware.

4. Are A/C component mounting bolts in place and tightly secured? Nothing loose or rattling around?
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5. Are caps installed on the A/C system service ports? This keeps out dirt, and also provides a sealfor refrigerant.

6. Check all belts for cracks, wear, and glazing. Have them replaced at the first sign of any of theseconditions. Also, check for belts that vibrate while the engine is running and the A/C is on. This mayindicate a belt that needs to be tightened, or a defectiveautomaticbelt tensioner.

7. Examine all A/C and cooling system hoses for cuts, abrasion, weak spots, and signs of leakage.Leakage from A/C system hoses is often indicated by an accumulation of dirt and oil, particularly atconnections and fittings.

8. Make sure the condenser (in front of theradiator) is free of any obstructions, such as leaves orinsects. This could reduce airflow, resulting in reduced A/C performance. You can rinse the condenser

clean with agarden hose.

Auto Air Conditioner Blowing Warm Air, Not CoolingCopyright AA1Car

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Is you car's air conditioner blowing warm air only and no cool air? Your A/C cooling problem could becaused by any of the following:

Your A/C system may have lost its charge of refrigerant, or the compressor may not be engaging whenyou turn on the A/C, or there may be an obstruction in the system, or the blend air door inside the HVACunit may be stuck in the HEAT position so no air goes through the A/C evaporator.

Compressor Checks
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Start with the compressor. Does it engage when you turn on the A/C?

If so, the compressor is working and the A/C system probably contains enough refrigerant to make coldair, so the problem is inside the HVAC unit. Replace the motor that controls the blend air door (this is adifficult job and best left to a professional since it involves tearing apart the HVAC unit -- about an 8 to 10hour job!).

If the compressor does not engage when you turn on the A/C, see if it will run by jumping the compressorclutch wire directly to the battery (use a fused jumper wire). If the compressor works when you jump it,and the A/C blows cold air, the system contains refrigerant and the fault is likely a bad A/C compressorclutch relay or a bad clutchcyclingswitch or pressure switch.

If the compressor does not engage when you jump it, the problem is a bad compressor clutch.

If the clutch engages but the compressor does not turn (the belt will start to slip and squeal), thecompressor is locked up and you need a new compressor.

If the compressor clutch engages and turns the compressor, but the A/C still does not blow cold air, the

system is probably low on refrigerant and needs to be recharged.

Refrigerant Checks

Connect an A/C pressure gauge to the HIGH SIDE service port (located in the high pressure hosethat runs between the compressor and the condenser in the front ofthe enginecompartment). The gaugewill tell you if there is any pressure in the system. Simply depressing the service fitting valve with a smallscrewdriver to see if any refrigerant squirts out is NOT an accurate check because it tell you how muchpressure is in the system. It may still have some pressure but not enough to trip the low pressure safetyswitch so the compressor will engage.

If your A/C system is low or out of refrigerant, check for leaks, then have the A/C system vacuumpurged

to remove air. After the air is out, it can be recharged with the specified amount of refrigerant. It isimportant to get any air out as this will reduce cooling efficiency and may make the compressor noisy.

A/C System Functional Checks

If the refrigeration circuit seems to be working (refrigerant in the system, compressor running andbuilding pressure), but there is still no cooling, the problem might be an obstruction in the orifice tube(located in the high pressure hose between the condenser in the front of the radiator, and the evaporatorlocated in the passenger compartment). A blockage here will prevent the refrigerant from entering theevaporator or recirculating through the refrigeration circuit.

If the orifice tube is plugged, the high side pressure reading will be lower than normal, and the low side

reading will also be lower than normal because no refrigerant is circulating through the system.

If the refrigeration circuit seems to be functioning normally (compressor running, frost orcondensation on the high pressure line from the condenser to the evaporator), but no cool air is blowingout of the ducts inside the car (and the blower is working), the fault is likely a BLEND AIR door that isstuck in the HEAT position, or possibly a badly clogged cabin air filter that is restricting airflow. Anotherpossibility would be a fault in theautomaticclimate control system such as a ad interior temperaturesensor or control module.
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My advice to you if you know nothing about A/C service is to find a repair shop that specializes in A/Crepairs and let them diagnose and repair your air conditioning cooling problem. Today's A/C systems withautomatic climate control are very complex and require special tools and know-how to diagnose andrepair.

A/C Gauge Readings

To determine the HIGH SIDE and LOW SIDE pressures inside your vehicle's air conditioning system, youneed an A/C Gauge Set. The Gauge Set must be connected to the A/C service ports on vehicle to read

the pressures while the system is running.

With the engine OFF, connect the A/C Gauge Set High Pressure Hose (the one with the larger couplerfitting) to the High Side service port (usually located in the compressor output line that goes from the

compressor to the condenser). Connect the Low Pressure Hose (the one with the smaller coupling) to theLow Side Service port (usually located on the accumulator, or on the suction hose that goes from the

evaporator to the compressor).

Start the engine, turn on the A/C to MAX, and rev the engine to 2000 RPM. Hold the engine speed andnote the High and Low side pressure gauge readings.

NOTE:High and Low side pressure readings will vary with ambient temperature and humidity. The higherthe temperature and/or humidity, the higher the gauge readings.

With late model R134a systems, good high pressure readings should range from 150 to 220 PSI at 80degrees F, 170 to 250 PSI at 90 degrees F, and 195 to 280 PSI at 100 degrees F.


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A High side pressure reading of less than 150 PSI indicates a low charge or a compressor problem. Ahigh pressure reading over 300 PSI would indicate an overcharge condition (too much refrigerant in

system) or a restriction in the high side.

Good low pressure readings with R134a should usually be in the 30 to 35 PSI range. If higher, there maybe a low side restriction. If the reading is lower, the system may be low on refrigerant.

With older R12 A/C systems (1994 model year vehicles an older that have NOT been retrofitted toR134a), the HIGH side pressure readings will typically be 150 to 185 PSI at 80 degrees F, 175 to 205 PSI

at 90 degrees F, and 200 to 250 PSI at 100 degrees F. Normal LOW side readings with R12 should bearound 20 to 30 PSI for an expansion valve system, or 15 to 40 PSI for an orifice tube system.

How To Recharge Your Car's Air ConditionerCopyright AA1Car

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LOW REFRIGERANT

If your air conditioner is not cooling well because the system is low on refrigerant, recharging the systemwith refrigerant should restore normal operation. This can usually be done with a few cans of refrigerantand a simple service hose connection.

RECHARGING PRECAUTIONS

First, wear safetyglassesto protect your eyes. Also avoid skin contact with refrigerant. The chilling effectof spilled refrigerant can cause instant frostbite on bare skin or eyes!

WHAT TYPE OF REFRIGERANT?

Next, you need to figure out what type of refrigerant your vehicle requires:On 1995 and newer passenger cars and light trucks, the correct refrigerant is R134a. DO NOT use anyother type of refrigerant.

On most 1994 and older passenger cars and light trucks, the original refrigerant was R12. R12 is nolonger available to do-it-yourselfers and is very expensive. When older vehicles with R12 A/C systemsneed refrigerant, they can be refilled with recycled R12 from other older cars (this requires taking your car
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to arepair shopfor professional service), or with somealternative refrigerantother than R12, or withR134a (which requires certain modifications).

CAUTION: Mixing different types of refrigerants is NOT recommended. Use the same type of refrigerantthat is already in the system unless you are converting an older R12 system to R134a or anotherrefrigerant.

WARNING: Flammable refrigerants are illegal. DO NOT use any type of flammable refrigerant (propane,butane or flammable hydrocarbons).

For more information, seeFlammable Refrigerants

Click herefor more information about retrofitting older vehicles with R12 A/C systems to R134a.

LOCATE THE SERVICE FITTINGS

Next, you need to locate the service fittings on the A/C system. There are two: a LOW side fitting and a

HIGH side fitting. The LOW side fitting is usually located on the suction hose or line that goes from the

accumulator to the compressor. The HIGH side fitting is located on the line that goes from the compressorto the condenser.

On older R12 systems, the LOW and HIGH pressure service fittings are screw-type schrader valves. Onnewer R134a systems, the LOW and HIGH side service fittings are quick-connect style fittings. The LOWpressure fitting is SMALLER than the HIGH pressure fitting.
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AIR CONDITIONING RECHARGE PROCEDURE

1. Connect the recharge service hose and valve to a can of refrigerant.

2. Turn the valve on the service hose to puncture the top of the can.

3. SLOWLY turn the valve back out to release a small amount of refrigerant into the hose. This will blow

air out of the hose (which you do not want in your A/C system).

4. Close the valve so no more refrigerant escapes, then quickly connect the other end of the service hose

to the LOW pressure service fitting on the A/C system.

CAUTION: DO NOT connect a can of refrigerant to the HIGH side service fitting. The operating pressure

inside the A/C system when it is running may exceed the burst strength of the can, causing the can to

explode! This should be impossible to do because the service hose for recharging the A/C system will

only fit the smaller LOW pressure service fitting. Even so, you should be aware of the danger.

5. Hold the can UPRIGHT so no refrigerant liquid enters the service hose. You only want VAPOR to be

pulled into the A/C system (the compressor may be damaged if it sucks in a big dose of liquid!).

6. OPTIONAL BUT HIGHLY RECOMMENDED: You should use a gauge to monitor the recharging

process. Though not absolutely necessary, a gauge will help you recharge your A/C system more

accurately, and reduce the chance of undercharging or overcharging (either of which will reduce cooling

performance).

A high pressure A/C gauge can be connected to the HIGH pressure service fitting, or a low pressure A/C

gauge to the LOW pressure service fitting, or gauges can be attached to both fittings (that is what

professionaltechniciansdo).

NOTE: Some DIY recharging kits include a low pressure gauge on the service hose or on a trigger-grip

style can dispenser.


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..

7. Startthe engineand turn the A/C on MAX/HIGH.

8. NOTE: The compressor may not engage if the system is too low on refrigerant. The low pressure

cutout switch will prevent the compressor from running if the system is too low on refrigerant (this is done

to protect the compressor from damage due to a lack of proper lubrication). The compressor must be

running to suck refrigerant through the service hose into the system. So if it is not engaging when you

turn the A/C on, you may have to supplybattery voltagedirectly to the compressor clutch using a fused

jumper wire. Look for a singlewire connectornear the front of the compressor, unplug it and hook up a

jumper wire to thebatteryPOSITIVE terminal. This should cause the clutch to engage and the

compressor to run.

9. OPEN the valve on the service hose so refrigerant vapor will flow from the can into the A/C system. It

may take up to 10 minutes or more per can to suck all of the refrigerant out of the can into the A/C

system. Feel the air coming out of the ducts inside the vehicle. It should be getting colder.

10. If you are using a high or low pressure gauge (or both) to monitor recharging, look at the gauge(s).

LOW pressure gauge: When the reading is between 25 and 40 psi with the A/C running, STOP. The

system is fully charged and should be cooling normally. DO NOT add any more refrigerant. If the gauge is

over 50 psi, you have overcharged the system with too much refrigerant.

High pressure gauge: When the reading gets up around 200 to

225 psi (R12), or225 to 250 psi (R134a), STOP. The system is

fully charged and should be cooling normally. DO NOT add any

more refrigerant.

NOTE: The high and low pressure readings will vary depending on

the system and ambient temperatures (higher temperatures cause

higher system pressure readings).

Refer to the vehicle manufacturer specifications for normal system

operating pressures, and the total refrigerant capacity of the system. Most newer passenger car A/C

systems do not hold much refrigerant (only 14 to 28 oz.), so you don't want to add too much if the system

is low. One can of R134a typically holds 12 oz. of refrigerant.

11. If the system needs more refrigerant after adding one can, you can add a second can. CLOSE the
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valve on the service hose, then disconnect the hose from the empty can, screw a new can onto the

service hose valve, turn the valve to puncture the new can, then turn the valve all the way back out again

so refrigerant can flow through the hose into the A/C system.

When you have finished, turn the engine off. CLOSE the valve on the can of refrigerant before

disconnecting the service hose from the LOW pressure fitting (in case there is any refrigerant left in the

can). Don't vent any left over refrigerant from the can. Leave the service hose attached to the can with the

valve closed so you can save the refrigerant for a future recharge.

Remember to replace the plastic caps over the service fittings, and remove the jumper wire from the

compressor if you had to jump it to make it run.

IF THE A/C SYSTEM STOPS BLOWING COLD AIR AFTER A FEW DAYS, WEEKS OR MONTHS

If your A/C stops blowing cold air several days, weeks or months after you recharged it, it means thesystem has a leak and the refrigerant is escaping. You should add some leak detectiondye to the systemto find the leak. The leak should then be repaired before the system is recharged again, otherwise youare just wasting your time recharging the system over and over again.

Documents

Troubleshoot Air Conditioning