Whirlpool WP4387489 Defrost Thermostat

The Whirlpool WP4387489 Defrost Thermostat is a crucial part of your refrigerator, offering efficient and safe defrost cycles. This bimetal thermostat acts as a temperature switch. It monitors the temperature within the evaporator coils, which are responsible for freezing air. When snow accumulates on the coils, reducing their capacity to absorb heat, the defrost thermostat kicks in. As the temperature ascends above a certain point, the bi-metal strip inside the thermostat bends, triggering a switch that shifts off the compressor and starts the defrost heater. This heater melts frost buildup, enabling the evaporator coils to function properly once again. Once the temperature drops below a particular level, the bi-metal strip resets, turning off the heater and resuming the compressor.