What is the purpose of a crankcase heater on a compressor?

The purpose of a crankcase heater on a compressor is primarily to prevent refrigerant migration during off cycles. When the system is not running, refrigerant can migrate to the compressor's crankcase, especially if the compressor is located in a colder environment. This migration can lead to issues such as liquid refrigerant being present in the crankcase when the compressor starts up, which can cause damage. A crankcase heater is used to maintain the crankcase temperature, ensuring that any refrigerant remains in a gaseous state, thus protecting the compressor and allowing for better reliability and performance when the system is turned back on.

While other options may touch on aspects of compressor operation, they do not accurately describe the main function of a crankcase heater. The heater does not cool the compressor, increase efficiency, or reduce noise levels directly, making the prevention of refrigerant migration the most crucial and relevant purpose.