Presentation on theme: "Trouble Shooting and Performance Testing"— Presentation transcript:
1 Trouble Shooting and Performance Testing CHAPTERTrouble Shooting and Performance Testing10Instructor Name: (Your Name)
2 Learning ObjectivesIdentify 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.
3 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.
4 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.
5 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.
6 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.
7 CAUTIONAir 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.
8 Air Conditioning Safety Safety glassesNon leather glovesProper ventilationRefrigerant must be stored below 125 degrees FahrenheitRefrigerant oil must be stored in air tight containersDo not mix refrigerant oils
9 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.
10 Servicing (continued) Prior to any service work is performed, talk to drive to obtain any problematic history of the unit. Questions should include;Did the A/C fail all at once or gradually loose its effectiveness?Does the A/C work occasionally or not at all?Has the A/C been worked on or serviced recently?
11 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 stabilizeCheck 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.
12 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.
13 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.
18 Gauge Reading, Some Air and Moisture in System SymptomsNot cooling effectivelyMoisture indicator show moisture level high in systemLow pressure cycling does not respond to the on/off cycle of thermostatic switchCauseAir or moisture in system. Probably caused by external leak in low side of the system.CureLeak test the systemRemove refrigerant, repair any leaks found
19 Gauge Reading, Some Air and Moisture in System (continued) Cure (continued)Flush and purge system if requiredTop up oil if requiredReplace the receiver dryerEvacuate the systemCharger with recommended weigh of refrigerant
20 Gauge Reading, Excessive Air and Moisture in System
21 Gauge Reading, Excessive Air and Moisture in System SymptomsNot cooling effectivelyMoisture indicator show moisture level high in systemSuction pressure is high in the beginning but as system operates may drop to low or even vacuumDischarge pressure is highCauseReceiver dryer saturated allowing moisture to freeze at the TXVHigh pressure caused by excess air in system
22 Gauge Reading, Excessive Air and Moisture in System (continued) CureLeak test the systemReclaim refrigerant, repair any leaksFlush and purge as requiredTop up refrigerant oilReplace receiver dryerEvacuate systemCharge with recommended weight of refrigerant
23 Gauge Reading, Obstructed Condenser or Over Charged System
24 Gauge Reading, Obstructed Condenser or Over Charged System SymptomNot cooling effectivelySuction line warmDischarge line too hotTruck engine may be overheatingHigh pressure relief open opening circuit to clutchCauseFan belt slipping, clutch fan faultyRefrigerant is excessively overcharged
25 Gauge Reading, Obstructed Condenser or Over Charged System (continued) CureClean condenser and radiator, do not use a pressure washerCheck condition and tension of fan belt. Check fan speed and replace clutch fan if necessaryRecover refrigerant. Top up oil if necessary. Charge with recommended weight of refrigerant.Test system pressure. If still high test for restriction in high side.
27 Gauge Reading, Low Refrigerant Charge SymptomsNot cooling effectivelySlightly lower than normal suction and discharge pressureCauseA very small leak in the A/C systemCureLeak test the systemRepair any leaks foundFlush and purge system if required
28 Gauge Reading, Low Refrigerant Charge(continued) CureTop of oil if requiredReplace receiver dryerEvacuate the systemCharge with recommended weight of refrigerant
30 Gauge Reading, Very Low Refrigerant Charge SymptomsNot coolingDischarge air from evaporator may be warmCompressor not running or cycling frequentlyLow pressure switch consistently openCauseLeak in air conditioning systemCureLeak test the A/C system
31 Gauge Reading, Very Low Refrigerant Charge (continued) Cure (continued)Recover refrigerant and repair any leaksFlush and purge system if neededRemove refrigerant and flush of requiredTop off oil if requiredReplace receiver dryerEvacuate systemCharge with recommended weight of refrigerant
32 Gauge Reading, Restriction in High Side of System
33 Gauge Reading, Restriction in High Side of System SymptomNot cooling effectivelyFrosted discharger line beyond restrictionIf restriction is between compressor and inlet of receiver, discharge pressure may be excessively highHigh pressure switch is openCauseRestriction between compressor discharge and inlet of TXV
34 Gauge Reading, Restriction in High Side of System (continued) CureFeel discharge line for cold spots to identify the point of restrictionRecover refrigerant and flush of requiredReplace defective component if it can’t be flushedTop up oil if requiredReplace receiver dryerEvacuate systemCharge with recommended weight of refrigerant
36 Gauge Reading, TXV Not Opening Enough SymptomsNot cooling effectivelySweat or frost build up on expansion valveSuction or discharge pressure return to normal if heat is applied to TXVCauseThe TXV does not open enoughThe TXV is stuck closedProblem with capillary tube or sensing bulbBlockage at the orifice tube in CCOT system
37 Gauge Reading, TXV Not Opening Enough (continued) CureRepair TXV if possible, if not go to Step 2Recover refrigerant and flush system if requiredReplace TXV, do not damage or crimp capillary tubeTop up refrigerant oilReplace receiver dryer or accumulatorEvacuate systemCharge with recommended weight of refrigerant
39 Gauge Reading, TXV Held Open SymptomNot cooling effectively, cools well in beginning but evaporator freezes over and blocks air flowSweat or frost build up on TXVSuction valve sweats heavilySystem pressure returns to normal if evaporator is allowed to defrostCauseThe TXV stuck open flooding evaporatorProblem with sensing bulb or capillary tube
40 Gauge Reading, TXV Held Open (continued) CureRepair TXV if possible, if not go to Step 2Recover refrigerant and flush if necessaryReplace TXV, be careful to not damage or crimp capillary tubeTop up oil if necessaryReplace receiver dryerEvacuate the systemCharge with recommended weight of refrigerant
42 Gauge Reading, Defective Thermostatic Switch SymptomsNot cooling effectively. Compressor runs constantly and may become noisyEvaporator freezes up, blocking air flowCauseDefective thermostatic switch not disengaging clutch at temp below 32 degree fBent, kinked, or broken capillary tube causing thermostatic switch to malfunction
43 Gauge Reading, Defective Thermostatic Switch (continued) CureInspect condition of capillary tube for thermostatic switch.Perform electrical test on the switchRectify any problems found with capillary tubeIf capillary tube can’t be corrected, replace thermostatic switch
45 Gauge Reading, Defective Compressor SymptomsNot cooling effectivelyNoisy compressor operation with no compressor cyclingCauseCompressor drive belt loose or wornCompressor clutch not operatingInternal compressor failureDefective trinary or low pressure switchCureInspect/replace compressor drive beltInspect/replace engine drive pulley
46 Gauge Reading, Defective Compressor (continued) Cure (continued)Inspect/replace compressor clutchTest trinary switch electrically, replace if necessaryIf compressor is replaced, flush systemTop off oil if necessaryReplace receiver dryerEvacuate systemCharge with recommended weight of refrigerant
47 Flushing and PurgingPurging blows out wet air, refrigerant, and loose dirt from systemFlushing is used to clean extremely contaminated systems.Purging, use dry nitrogen.HCFC 141b. Is commonly approved by system manufacturersSome manufactures do not endorse flushing and are not covered under their warranty.
48 Summary A/C systems are constantly under pressure. Always wear appropriate PPE when working on a charged A/C systemR-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.
49 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.
50 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.
51 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.