A crankcase heater is a small heating element located at the base of the compressor in the outdoor unit. Its job is to keep the compressor oil warm during cold weather to prevent refrigerant from mixing with the oil. This ensures that the compressor has proper lubrication the moment it starts up on a chilly morning. You will find this feature standard on our Hyper Heat / Arctic Heat models. Without this heater, the compressor can suffer from "slugging," which can lead to permanent mechanical failure. It is a vital component for anyone using their Heat Pump System in regions that experience freezing temperatures. The heater typically turns on automatically when the outdoor temperature drops below a certain threshold. We stock Replacement Heaters for various models to keep your system protected through the winter. It is a small part that plays a massive role in extending the life of your expensive compressor.