Compressor Failures: Protection Devices, Symptoms, and Root Causes

The short field answer:
Most compressor failures are not “bad luck.” They are usually the end result of overheating, floodback, loss of charge, poor oil return, reverse rotation, contamination, or high compression stress. Copeland’s own literature is blunt: a large share of field compressor failures originate in overheating. 

Copeland documents several protection concepts: internal overload protection, internal temperature protection through a Therm-O-Disc type device, and in some models pressure-relief behavior. It also warns that loss of charge can cause overheating and overload recycling, and that prolonged operation like that can end in oil pump-out and bearing failure. For three-phase scrolls, reverse rotation shows up as abnormal sound with little pressure difference, and repeated reverse running can damage bearings because oil is lost to the system. 

The technician rule that saves money:
Never replace a compressor until you can answer why it died. If you cannot name the root cause, you are probably installing the next failure.