The Whirlpool WP4387499 Bi-Metal Defrost Thermostat regulates the refrigerator’s defrost cycle by monitoring the temperature near the evaporator. This temperature-sensitive component controls the defrost heater circuit, allowing the heater to operate when frost needs to be removed and stopping it when the temperature reaches the thermostat’s specified limit. Proper defrost control hel... https://www.partsmelange.ca/whirlpool-wp4387499-bi-metal-defrost-thermostat-for-refrigerator