Troubleshooting

15-47spec table

NOTE

Performance Test on page 15-59.

Test Results	Related Symptoms	Probable Cause	Remedy
Discharge (high) pressure abnormally high	After stopping compressor, pressure drops to about 196 kPa (28 psi) quickly, and then falls gradually	Air in system	Evacuate system; then recharge. Evacuation: page 15-56. Recharging: 15-58
Discharge (high) pressure abnormally high	No bubbles in sight glass when condenser is cooled by water	Excessive refrigerant in system	Discharge refrigerant as required
Discharge (high) pressure abnormally high	Reduced or no air flow through condenser.	• Clogged condenser or radiator fins • Condenser or radiator fan not working properly	• Clean • Check voltage and fan rpm
Discharge (high) pressure abnormally high	Line to condenser is excessively hot	Restricted flow of refrigerant in system	Expansion valve
Discharge pressure abnormally low	Excessive bubbles in sight glass; condenser is not hot	Insufficient refrigerant in system	• Charge system • Check for leak
Discharge pressure abnormally low	High and low pressures are balanced soon after stopping compressor	• Faulty compressor discharge or inlet valve • Faulty compressor seal	Replace compressor. Repair
Discharge pressure abnormally low	Outlet of expansion valve is not frosted, low pressure gauge indicates vacuum	• Faulty expansion valve	Repair or Replace
Suction (low) pressure abnormally low	Excessive bubbles in sight glass; condenser is not hot. Expansion valve is not frosted and low pressure line is not cold. Low pressure gauge indicates vacuum.	Insufficient refrigerant • Frozen expansion valve • Faulty expansion valve	Check for leaks. Charge as required. Replace expansion valve
Suction (low) pressure abnormally low	Discharge temperature is low and the air flow from vents is restricted	Frozen evaporator	Run the fan with compressor off then check the thermostat and capillary tube.
Suction (low) pressure abnormally low	Expansion valve frosted	Clogged expansion valve	Clean or Replace
Suction (low) pressure abnormally low	Receiver dryer is cool (should be warm during operation)	Clogged receiver dryer	Replace
Suction pressure abnormally high	Low pressure hose and check joint are cooler than around evaporator	• Expansion valve open too long • Loose expansion valve	Repair or Replace
Suction pressure abnormally high	Suction pressure is lowered when condenser is cooled by water	Excessive refrigerant in system	Discharge refrigerant as necessary
Suction pressure abnormally high	High and low pressure are equalized as soon as the compressor is stopped	• Faulty gasket • Faulty high pressure valve • Foreign particle stuck in high pressure valve	Replace compressor
Suction and discharge pressures abnormally high	Reduced air flow through condenser	• Clogged condenser or radiator fins • Condenser or radiator fan not working properly	• Clean condenser and radiator • Check voltage and fan rpm
Suction and discharge pressures abnormally high	No bubbles in sight glass when condenser is cooled by water	Excessive refrigerant in system	Discharge refrigerant as necessary.
Suction and discharge pressure abnormally low	Low pressure hose and metal end areas are cooler than evaporator	Clogged or kinked low pressure hose parts	Repair or Replace
Suction and discharge pressure abnormally low	Temperature around expansion valve is too low compared with that around receiver-driver.	Clogged high pressure line	Repair or Replace
Refrigerant leaks	Compressor clutch is dirty	Compressor shaft seal leaking	Replace compressor shaft seal
Refrigerant leaks	Compressor bolt(s) are dirty	Leaking around bolt(s)	Replace compressor
Refrigerant leaks	Compressor gasket is wet with oil	Gasket leaking	Replace compressor

Discharge (high) pressure abnormally high

Related SymptomsAfter stopping compressor, pressure drops to about 196 kPa (28 psi) quickly, and then falls gradually

Probable CauseAir in system

RemedyEvacuate system; then recharge. Evacuation: page 15-56. Recharging: 15-58

Discharge (high) pressure abnormally high

Related SymptomsNo bubbles in sight glass when condenser is cooled by water

Probable CauseExcessive refrigerant in system

RemedyDischarge refrigerant as required

Discharge (high) pressure abnormally high

Related SymptomsReduced or no air flow through condenser.

Probable Cause• Clogged condenser or radiator fins • Condenser or radiator fan not working properly

Remedy• Clean • Check voltage and fan rpm

Discharge (high) pressure abnormally high

Related SymptomsLine to condenser is excessively hot

Probable CauseRestricted flow of refrigerant in system

RemedyExpansion valve

Discharge pressure abnormally low

Related SymptomsExcessive bubbles in sight glass; condenser is not hot

Probable CauseInsufficient refrigerant in system

Remedy• Charge system • Check for leak

Discharge pressure abnormally low

Related SymptomsHigh and low pressures are balanced soon after stopping compressor

Probable Cause• Faulty compressor discharge or inlet valve • Faulty compressor seal

RemedyReplace compressor. Repair

Discharge pressure abnormally low

Related SymptomsOutlet of expansion valve is not frosted, low pressure gauge indicates vacuum

Probable Cause• Faulty expansion valve

RemedyRepair or Replace

Suction (low) pressure abnormally low

Related SymptomsExcessive bubbles in sight glass; condenser is not hot. Expansion valve is not frosted and low pressure line is not cold. Low pressure gauge indicates vacuum.

Probable CauseInsufficient refrigerant • Frozen expansion valve • Faulty expansion valve

RemedyCheck for leaks. Charge as required. Replace expansion valve

Suction (low) pressure abnormally low

Related SymptomsDischarge temperature is low and the air flow from vents is restricted

Probable CauseFrozen evaporator

RemedyRun the fan with compressor off then check the thermostat and capillary tube.

Suction (low) pressure abnormally low

Related SymptomsExpansion valve frosted

Probable CauseClogged expansion valve

RemedyClean or Replace

Suction (low) pressure abnormally low

Related SymptomsReceiver dryer is cool (should be warm during operation)

Probable CauseClogged receiver dryer

RemedyReplace

Suction pressure abnormally high

Related SymptomsLow pressure hose and check joint are cooler than around evaporator

Probable Cause• Expansion valve open too long • Loose expansion valve

RemedyRepair or Replace

Suction pressure abnormally high

Related SymptomsSuction pressure is lowered when condenser is cooled by water

Probable CauseExcessive refrigerant in system

RemedyDischarge refrigerant as necessary

Suction pressure abnormally high

Related SymptomsHigh and low pressure are equalized as soon as the compressor is stopped

Probable Cause• Faulty gasket • Faulty high pressure valve • Foreign particle stuck in high pressure valve

RemedyReplace compressor

Suction and discharge pressures abnormally high

Related SymptomsReduced air flow through condenser

Probable Cause• Clogged condenser or radiator fins • Condenser or radiator fan not working properly

Remedy• Clean condenser and radiator • Check voltage and fan rpm

Suction and discharge pressures abnormally high

Related SymptomsNo bubbles in sight glass when condenser is cooled by water

Probable CauseExcessive refrigerant in system

RemedyDischarge refrigerant as necessary.

Suction and discharge pressure abnormally low

Related SymptomsLow pressure hose and metal end areas are cooler than evaporator

Probable CauseClogged or kinked low pressure hose parts

RemedyRepair or Replace

Suction and discharge pressure abnormally low

Related SymptomsTemperature around expansion valve is too low compared with that around receiver-driver.

Probable CauseClogged high pressure line

RemedyRepair or Replace

Refrigerant leaks

Related SymptomsCompressor clutch is dirty

Probable CauseCompressor shaft seal leaking

RemedyReplace compressor shaft seal

Refrigerant leaks

Related SymptomsCompressor bolt(s) are dirty

Probable CauseLeaking around bolt(s)

RemedyReplace compressor

Refrigerant leaks

Related SymptomsCompressor gasket is wet with oil

Probable CauseGasket leaking

RemedyReplace compressor

Support our work!

Troubleshooting

Search Manual