The Whirlpool WP4387501 serves as a bi-metal defrost thermostat, and it's a vital component in refrigerators that governs the defrost cycle. This automatic operation removes frost growth within the freezer compartment. The defrost thermostat, which is made up of two distinct metals joined together, reacts to changes in temperature. When the freezer temperature surpasses an established limit, the bi-metal strip bends, preventing the flow of electricity to the compressor. This shuts off the cooling cycle and activates the defrost heater, which melts any residual frost. When the temperature rises to a certain point, the bi-metal strip bends back, restarting the compressor and resuming normal cooling action. This enables effective defrosting, preventing excessive ice development, which may reduce the cooling process and waste energy.
