GAUGE READINGS
OTHER SYMPTOMS
DIAGNOSIS
CORRECTION
Discharge air : slightly cool.
Thermostatic switch (with thermistor) : Low side gauge doesn't fluctuate with "ON" and "OFF".
Some air and moisture in system.
Check for leaks.
Discharge refrigerant from system.
Repair leaks as located.
Evacuate the system for at least 30 minutes.
Charge system with refrigerant.
Operate system and check performance.
Discharge air : Becomes warm all the time during hot part of day.
Some air and moisture in system.
Discharge refrigerant.
Evacuate system with a vacuum pump.
Recharge system to proper capacity.
Operate system and check performance.
Compressor : Cycles on and off too fast.
Defective thermostatic switch.
Replace thermostatic switch.
Operate system and check performance.
Compressor : Low side pressure builds too high before compressor turns on (cycle "ON" point too high).
Faulty thermostatic switch.
Replace the thermostatic switch.
Operate system and check performance.
Discharge air : Slightly cool.
System slightly low on refrigerant.
Check for leaks.
Discharge refrigerant.
Repair leaks.
Evacuate system using a vacuum pump.
Charge system with refrigerant.
Operate system and check performance.
Discharge air : Warm
System very low on refrigerant.
Possible leak in system.
Check for leaks.
Discharge refrigerant.
Evaporate system using a vacuum pump.
Charge system with refrigerant.
Operate system and check performance.
Discharge air : Slightly cool.
Expansion valve : Frost build up.
Expansion valve stuck.
Screen plugged.
Sensing bulb malfunction.
Discharge system.
Disconnect inlet line at expansion valve and remove and inspect screen.
Replace screen and reconnect inlet line.
Evacuate system using a vacuum pump.
Charge system with refrigerant.
Discharge air : Slightly cool.
High side pipe : Cool and also shows moisture or frost.
Restriction in high side of system
Discharge system.
Evacuate system using a vacuum pump.
Charge system with refrigerant.
Operate system and check performance.
Compressor : Noisy
Compressor malfunction
Disassemble compressor.
Inspect compressor.
Check compressor oil level.
Operate system and check performance.
Discharge air : Warm
High side pipe : Very hot
Faulty condenser.
Overcharged.
Check for loose or worn fan belt.
Inspect condenser for clogged air passage.
Check for refrigerant overcharge.
Operate system and check performance.
Discharge air : Slightly cool.
Large amount of air and moisture.
Discharge refrigerant from system.
Evacuate system using vacuum pump.
Charge system with refrigerant.
Operate system and check performance.
Discharge air : Warm
Evaporator : Moisture or frost.
Expansion valve stuck.
Discharge system.
Replace expansion valve.
Evacuate system using vacuum pump, then recharge system with refrigerant.
Operate system and check performance.
