A fan-motor failure on an air-conditioning or refrigeration system usually is a catastrophic event because it often goes unnoticed for a while and puts great stress on the system’s compressor, thus shortening its life.
An evaporator (indoor) fan-motor failure almost always results in the indoor coil freezing over and the suction line freezing all the way back to the compressor. And since the refrigerant isn’t being evaporated in the coil, liquid refrigerant is being drained back into the compressor. Then the natural law comes into play: “You can’t compress a liquid.” So on some compressor designs, this destroys the internal valves. But on all compressor designs, the liquid refrigerant dilutes the lubricant, which often results in a locked-rotor condition.