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CHAPTER. Trouble Shooting and Performance Testing. 10. Instructor Name: (Your Name ). Learning Objectives. Identify proper safety equipment worn when servicing HVACR systems. Explain how to work safely on pressurized HVACR systems. - PowerPoint PPT Presentation
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Copyright © 2014 Delmar, Cengage Learning
Trouble Shooting and Performance Testing
Instructor Name: (Your Name)
10CHAPTER
Copyright © 2014 Delmar, Cengage Learning
Learning Objectives Identify proper safety equipment worn when
servicing HVACR systems. Explain how to work safely on pressurized
HVACR systems. List rules that should be followed whenever a
system has been opened to atmosphere. Explain how to performance test an HVACR
system.
Copyright © 2014 Delmar, Cengage Learning
Learning Objectives (continued)
Identify a system that contains some air and moisture.
Identify a system that has excessive air and moisture.
Identify a system that has restricted air flow through the condenser or is overcharged.
Identify a system that has a low refrigerant charge.
Copyright © 2014 Delmar, Cengage Learning
Learning Objectives (continued)
Identify a system that has a very low refrigerant charge.
Identify a system that is overcharged with refrigerant.
Identify a system that has a restriction in the high pressure side of system.
Identify a system that has a TXV that will not open.
Copyright © 2014 Delmar, Cengage Learning
Learning Objectives (continued)
Identify a system that has a TXV held open. Identify a system that has a defective
thermostat switch. Identify a system that has a defective
compressor. Identify the difference between purging and
flushing an A/C system. List the procedures for purging an A/C system.
Copyright © 2014 Delmar, Cengage Learning
Learning Objectives (continued)
Explain the procedures for flushing an A/C sys.
Explain how to pop dry a system after a full flush has been performed.
Copyright © 2014 Delmar, Cengage Learning
CAUTION
Air conditioning systems are always under pressure. Before internal system repairs are made refrigerant must be recovered from system. Once repairs are complete the system must be evacuated and recharged before it can be returned to service.
Copyright © 2014 Delmar, Cengage Learning
Air Conditioning Safety
Safety glasses Non leather gloves Proper ventilation Refrigerant must be stored below 125 degrees
Fahrenheit Refrigerant oil must be stored in air tight
containers Do not mix refrigerant oils
Copyright © 2014 Delmar, Cengage Learning
Servicing When system is open cap disconnected lines. Replace and lubricate all o-rings on
disconnected lines. Replace receiver dryer or accumulator on
opened system. Keep manifold gauge set connected when
servicing. Replace all lost refrigerant oil.
Copyright © 2014 Delmar, Cengage Learning
Servicing (continued) Prior to any service work is performed, talk to
drive to obtain any problematic history of the unit. Questions should include;1. Did the A/C fail all at once or gradually loose its
effectiveness?2. Does the A/C work occasionally or not at all?3. Has the A/C been worked on or serviced
recently?
Copyright © 2014 Delmar, Cengage Learning
Performance Testing Run engine at 1500 rpm, close all windows Run A/C on max for minimum 10 minutes to
stabilize system. Insert thermometer in air vent, let system stabilize Check for proper vent and fan operation. Visually inspect compressor, compressor clutch, and
drive belt. Feel the suction and discharge lines at compressor.
Suction line should be cold and discharge line should be hot.
Copyright © 2014 Delmar, Cengage Learning
Performance Testing Cont.
Feel condenser inlet and outlet line there should be a large change in temperature.
Feel condenser to receiver dryer line, feel for warm or cold spots.
Feel inlet and outlet of receiver dryer, they should be the same temperature.
Feel outlet of receiver dryer to TXV line, it should be a consistent temperature.
Copyright © 2014 Delmar, Cengage Learning
Performance Testing Cont.
Feel the suction line from evaporator to compressor, it should be cold.
If engine is running hot or heater water valve is stuck open the system will not cool.
Check discharge air temperature. It will vary according to ambient temp and humidity.
Shut down unit. Feel condenser for cold spots indicating
restrictions.
Copyright © 2014 Delmar, Cengage Learning
Troubleshooting Flow Chart
Copyright © 2014 Delmar, Cengage Learning
Manifold Gauge Set Connection
Copyright © 2014 Delmar, Cengage Learning
Pressure Temperature Chart
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Some Air and Moisture in System
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Some Air and Moisture in System
• Symptoms1. Not cooling effectively2. Moisture indicator show moisture level high in system3. Low pressure cycling does not respond to the on/off cycle
of thermostatic switch• Cause Air or moisture in system. Probably caused by external leak in
low side of the system.• Cure
1. Leak test the system2. Remove refrigerant, repair any leaks found
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Some Air and Moisture in System (continued)
• Cure (continued)3. Flush and purge system if required4. Top up oil if required5. Replace the receiver dryer6. Evacuate the system7. Charger with recommended weigh of refrigerant
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Excessive Air and Moisture in System
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Excessive Air and Moisture in System
• Symptoms1. Not cooling effectively2. Moisture indicator show moisture level high in
system3. Suction pressure is high in the beginning but as
system operates may drop to low or even vacuum4. Discharge pressure is high• Cause1. Receiver dryer saturated allowing moisture to freeze
at the TXV2. High pressure caused by excess air in system
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Excessive Air and Moisture in System (continued)
• Cure1. Leak test the system2. Reclaim refrigerant, repair any leaks3. Flush and purge as required4. Top up refrigerant oil5. Replace receiver dryer6. Evacuate system7. Charge with recommended weight of refrigerant
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Obstructed Condenser or Over Charged System
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Obstructed Condenser or Over Charged System
• Symptom1. Not cooling effectively2. Suction line warm3. Discharge line too hot4. Truck engine may be overheating5. High pressure relief open opening circuit to clutch• Cause1. Fan belt slipping, clutch fan faulty2. Refrigerant is excessively overcharged
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Obstructed Condenser or Over Charged System (continued)
• Cure1. Clean condenser and radiator, do not use a pressure
washer2. Check condition and tension of fan belt. Check fan
speed and replace clutch fan if necessary3. Recover refrigerant. Top up oil if necessary. Charge
with recommended weight of refrigerant.4. Test system pressure. If still high test for restriction
in high side.
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Low Refrigerant Charge
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Low Refrigerant Charge
• Symptoms1. Not cooling effectively2. Slightly lower than normal suction and discharge
pressure• Cause1. A very small leak in the A/C system• Cure1. Leak test the system2. Repair any leaks found3. Flush and purge system if required
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Low Refrigerant Charge(continued)
• Cure4. Top of oil if required5. Replace receiver dryer6. Evacuate the system7. Charge with recommended weight of refrigerant
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Very Low Refrigerant Charge
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Very Low Refrigerant Charge
• Symptoms1. Not cooling2. Discharge air from evaporator may be warm3. Compressor not running or cycling frequently4. Low pressure switch consistently open• Cause1. Leak in air conditioning system• Cure1. Leak test the A/C system
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Very Low Refrigerant Charge (continued)
• Cure (continued)2. Recover refrigerant and repair any leaks3. Flush and purge system if needed4. Remove refrigerant and flush of required5. Top off oil if required6. Replace receiver dryer7. Evacuate system8. Charge with recommended weight of refrigerant
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Restriction in High Side of System
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Restriction in High Side of System
• Symptom1. Not cooling effectively2. Frosted discharger line beyond restriction3. If restriction is between compressor and inlet of
receiver, discharge pressure may be excessively high4. High pressure switch is open• Cause1. Restriction between compressor discharge and inlet
of TXV
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Restriction in High Side of System (continued)
• Cure1. Feel discharge line for cold spots to identify the
point of restriction2. Recover refrigerant and flush of required3. Replace defective component if it can’t be flushed4. Top up oil if required5. Replace receiver dryer6. Evacuate system7. Charge with recommended weight of refrigerant
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, TXV Not Opening Enough
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, TXV Not Opening Enough
• Symptoms1. Not cooling effectively2. Sweat or frost build up on expansion valve3. Suction or discharge pressure return to normal if
heat is applied to TXV• Cause1. The TXV does not open enough2. The TXV is stuck closed3. Problem with capillary tube or sensing bulb4. Blockage at the orifice tube in CCOT system
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, TXV Not Opening Enough (continued)
• Cure1. Repair TXV if possible, if not go to Step 22. Recover refrigerant and flush system if required3. Replace TXV, do not damage or crimp capillary tube4. Top up refrigerant oil5. Replace receiver dryer or accumulator6. Evacuate system7. Charge with recommended weight of refrigerant
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, TXV Held Open
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, TXV Held Open
• Symptom1. Not cooling effectively, cools well in beginning but
evaporator freezes over and blocks air flow2. Sweat or frost build up on TXV3. Suction valve sweats heavily4. System pressure returns to normal if evaporator is
allowed to defrost• Cause1. The TXV stuck open flooding evaporator2. Problem with sensing bulb or capillary tube
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, TXV Held Open (continued)
• Cure1. Repair TXV if possible, if not go to Step 22. Recover refrigerant and flush if necessary3. Replace TXV, be careful to not damage or crimp
capillary tube4. Top up oil if necessary5. Replace receiver dryer6. Evacuate the system7. Charge with recommended weight of refrigerant
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Defective Thermostatic Switch
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Defective Thermostatic Switch
• Symptoms1. Not cooling effectively. Compressor runs constantly
and may become noisy2. Evaporator freezes up, blocking air flow• Cause1. Defective thermostatic switch not disengaging
clutch at temp below 32 degree f2. Bent, kinked, or broken capillary tube causing
thermostatic switch to malfunction
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Defective Thermostatic Switch (continued)
• Cure1. Inspect condition of capillary tube for thermostatic
switch.2. Perform electrical test on the switch3. Rectify any problems found with capillary tube4. If capillary tube can’t be corrected, replace
thermostatic switch
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Defective Compressor
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Defective Compressor
• Symptoms1. Not cooling effectively2. Noisy compressor operation with no compressor cycling• Cause1. Compressor drive belt loose or worn2. Compressor clutch not operating3. Internal compressor failure4. Defective trinary or low pressure switch• Cure1. Inspect/replace compressor drive belt2. Inspect/replace engine drive pulley
Copyright © 2014 Delmar, Cengage Learning
Gauge Reading, Defective Compressor (continued)
• Cure (continued)3. Inspect/replace compressor clutch4. Test trinary switch electrically, replace if necessary5. If compressor is replaced, flush system6. Top off oil if necessary7. Replace receiver dryer8. Evacuate system9. Charge with recommended weight of refrigerant
Copyright © 2014 Delmar, Cengage Learning
Flushing and Purging
Purging blows out wet air, refrigerant, and loose dirt from system
Flushing is used to clean extremely contaminated systems.
Purging, use dry nitrogen. HCFC 141b. Is commonly approved by system
manufacturers Some manufactures do not endorse flushing and
are not covered under their warranty.
Copyright © 2014 Delmar, Cengage Learning
Summary A/C systems are constantly under pressure. Always wear appropriate PPE when working
on a charged A/C system R-134a can be combustible under the right
conditions. A/C system should never be pressure or leak
tested with compressed air, a fire or explosion could result.
Copyright © 2014 Delmar, Cengage Learning
Summary cont. PAG oil containers should always be kept
tightly closed. When a system is open, always cap
disconnected lines. Whenever A/C lines are disconnected always
replace and lubricate o-rings. Receiver driers must be replaced when a system
is opened. Manifold gauge fittings should be connected to
manifold when not in use.
Copyright © 2014 Delmar, Cengage Learning
Summary cont. Add refrigerant oil to replace any that may have
been lost. Always question operator about problems and
history of problems. Performance tests identify problems that may
exist. To check levels of R-134a, a performance test
with gauge set must conducted. If refrigerant is low, repair leaks, recover all coolant and refill. DO NOT TOP OFF SYSTEM.
Copyright © 2014 Delmar, Cengage Learning
Summary cont.
Use dry nitrogen to purge wet air and loose dirt from and A/C system.
Use liquid flushing agents to clean contaminants from A/C components.
Popping components dry is a process of drying A/C components with quick shots of dry nitrogen.