Residential systems use scroll, rotary or reciprocating compressors, mostly hermetically sealed with the motor cooled by suction gas. Larger systems use semi-hermetic reciprocating, screw and centrifugal machines. Compressors are built to pump vapor only: liquid returning to them washes out oil and can break valves or scrolls. Low suction pressure, high discharge pressure and poor oil return shorten their life.
Compressor's drawing 28 amps on a 22 RLA nameplate, it's working way too hard, check head pressure.
Before condemning a compressor, check the capacitor, the contactor and the supply voltage; those three cause most no-start calls.
Also heard as
- comp
- pot
Related terms
Slugging
Liquid refrigerant or oil being drawn into a compressor's cylinders, where it can't be compressed and causes damage.
LRA
Locked rotor amps: the current a motor draws at the instant of starting, before it turns, listed on the nameplate.
Burnout
A compressor motor failure that overheats the windings and contaminates the system with acid, sludge and carbon.
Head pressure
The compressor discharge or condensing pressure of a refrigeration system.