20
System troubleshooting.
symptoms
Possible causes
Solution
Compressor
not running
Main switch open
Close switch
Blown fuse
Check electrical circuits and
motor winding for shorts or
grounds.
Replace fuse after fault is
corrected.
Loose wiring
Check all wire junctions. Tighten
all terminal screws.
System cable shut down
Replace shutdown cable.
Thermal overload tripped
Overloads are automatically
reset. Check unit when unit come
back on line.
Defective contactor or contactor coil Replace or repair
System shut down by safety devices. Check cause of shut down
Liquid line solenoid not open
Repair or replace coil
Noisy
Compressor
Flooding of liquid refrigerant into
crankcase
Check expansion valve setting
Improper piping support on suction or
liquid line.
Relocate add hangers.
Worn compressor.
Replace compressor
High
discharge
pressure.
Non-condensable in system.
Remove non-condensable.
Too much refrigerant
Remove excess refrigerant
Discharge shut off valve partially
closed
Open valve
Fan not running
Check electrical circuit and fuse.
Dirty condenser coil
Clean condenser coil
Low discharge
pressure.
Faulty condenser temperature controls Check head pressure control
Suction shut off valve partially closed Open valve
Insufficient refrigerant
Check leaks. Add charge.
Low suction pressure
See corrective steps for low
suction pressure.
