What is the purpose of a crankcase heater in an air conditioning system?

The purpose of a crankcase heater in an air conditioning system is primarily to prevent refrigerant migration to the compressor during off cycles. When the air conditioning system is not running, especially during periods of low temperatures, refrigerant can condense in the evaporator coil and migrate back to the compressor. This is problematic because liquid refrigerant can damage the compressor when it starts up, leading to mechanical failure.

By using a crankcase heater, the internal temperature of the compressor is maintained at a level that keeps the refrigerant in a gaseous state. This ensures that when the system starts, only vapor enters the compressor, thereby enhancing the compressor's longevity and reliability. Proper function of the crankcase heater is crucial for maintaining the overall health of the air conditioning system, particularly in regions where the temperature can drop significantly during the night or off-season months.