22
symptoms
Possible causes
Solution
High suction
pressure
Excessive loads
Reduce load.
Expansion valve overfeeding.
Check bulb location and clamping.
Adjust superheat.
Low suction
pressure.
Lack of refrigerant.
Check for leaks. Add charge.
Evaporator dirty or iced
Clean and defrost.
Clogged liquid line filter drier.
Replace filter drier.
Expansion valve malfunctioning.
Check and reset for proper
superheat.
Condensing temperature too low.
Check and replace head pressure
control
Improper expansion valve.
Check for proper expansion
valve.
Compressor
thermal
protector
switch open.
Operating beyond design conditions
Add facilities so that conditions
are within allowable limits.
Discharge valve partially closed
Open valve.
Dirty condenser coil
Clean coil
Overcharged refrigerant
Reduce charge.
Compressor
loses oil
Lack of refrigerant
Check
for
leaks
and
add
refrigerant
Excessive compression ring blow by. Replace compressor.
Refrigerant flood back.
Maintain proper superheat at
compressor.
Improper piping or traps.
Correct piping.
Little or no oil
pressure
Clogged suction oil strainer.
Clean.
Excessive liquid in crankcase.
Check crankcase heater.
Adjust expansion valve.
Check the solenoid valve.
Low
oil
pressure
safety
switch
defective.
Replace.
Oil pump reversing gear stuck in
wrong position.
Reverse direction of compressor
rotation.
Worn bearings.
Replace compressor.
Low oil level.
Add oil.
Loose fitting on oil lines.
Check and tighten system.
Pump housing gasket leaks.
Peplace gasket.
