The defrost thermostat snaps onto the top portion of the evaporator. It acts as a safety device and protects the evaporator from overheating during the defrost cycle. The thermostat can sense the rise in the evaporator temperature during the defrost cycle and cycles the defrost heater off after all the frost is melted from the coils. This limiter thermostat will cut out when the temperature inside your refrigerator reaches 55 degrees Fahrenheit and kicks back in when the internal temperature drops to 20 degrees Fahrenheit. The defrost thermostat may need to be replaced if the appliance is experiencing temperature-related issues. This is a genuine OEM part. It is recommended to disconnect the power to your appliance before starting your repair.