A/C System Service
Pressure Test Chart
NOTE: Performance Test is on page 22-56.
Test resultsRelatad symptomsPrcbable caus€Remody
Discharge (high)pressure 6bnormallyhagh
After stopping compressor, pressuredrops to about 200 kPa 12.0 kgtlcm,,28 psi) quickly, and then lalls gradualty.
Air in systemDischarge, evacuate, and rechargewith specified amount.Evacuation: see page 22-60Charging: see page 22-61No bubbles in sight glass whencondenser is cooled by waterExcessive refrigerant in systemDischarge, evacuate, and rechargewith specilied amount.Reduced or no air flow throughcondenser. Clogged condenser or radia-tor fins. Condenser or radiator fannot wo.king properly
CleanCheck voltage and fan rpm.Check fan direction.
Line to condensor is excossivelv hot.Restricted flow of relrigerant insy$emFestricted lines
Discharge pressureabnormally lowExcessive bubbles in sight glass;condenser is not hot.Insufficient retrigerant inCheck for leak.Charge system.High and low pressures are balancedsoon after stopping compressor. Lowside is higher than normal.
. Faulty compressor discharge
. Faulty compressor seal
Replace the comprossor.
Outlet ot expansion valve is notfrosted, low-pressure gauge indicates
' Faulty expansion valve. Moisture in system. Replace. Discharge, evacuate, andrecharge with specified amount.Suction {low) pros,sure abnormallyExcessive bubbles in sight glass;condenser is not hot.Insufficiont relrigerant inRepair the leaks.Discharge, evacuate, andrecharge with specified amount.Charge as r€quired.Expansion valve is not frosted, andlow-pressure line is not cold. Low-pressure gauge indicates vacuum.
' Frozen expansion valvelMoisture in system). Faulty expansion valve
. Discharge, evacuate, andrecharge with specitied amount.. Replace th€ expansion valve.Discharge temperature is low, and theair llow trom vents is restricted.Frozen evaporatorRun the fan with compressor off,then check evaporator tempera,ture sensor.Expansion valve is frosted.Clogged expansion valveClean or replace.Feceiver/dryer outlet is cool, and inlotrs w6rm (should be warm duringoperation).
Clogged receiver/dryerReplace
Suction pressureabnormally highLow-pressure hose and check joint arecooler than tho temperature aroundevaporator.
. Expansion valve open too long. Loose expansion capillarytube
Repair or roplace.
Suction pressure is lowored whencondenser is cooled by water.Excessive refrigerant in systemDischarge, evacuate, and rechargewath specified amount.High and low-pressure are equalizedas soon as tho compressor is stopped,and both gauges tluctuate whilerunning.
Faulty gasketFaulty high-pressure valveForeign panicle stuck in high-
Replace the compressor.
Slction and dis,charge pressutesabnormally high
Reduced air flow through condens€r,. Clogged condenser orradiator tins. Condenser or radiator fannot working properly
CleanCheck voltage and fan rpm.Check Ian direction.
No bubbles in sight glass whencondenser is cooled by walerExcessive refrigerant jn systemDischarge, evacuate, and rechargewith specified amount.Suction and dis-charge pressureabnormally low
Low-pressure hose and motalendareas are cooterlhan evaporator.Clogged or kinked low-pressure hose pansRepair or replace.
Temperature around expansion valvers too low compared with that aroundClogged high-pressure lineRepair or replace.
Refrigerant leaksCompressor clutch is diny.Compressor shaft seal leakingReplace the compressor.Compressor boltls) are dirty.Leaking around bolt(s)Tighton bolt{s) or replacecompressor.Compressor gasket is wet with oil.Gasket leakingReplace the compressor,
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