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. The defrost thermostat may need to be replaced if the appliance is experiencing temperature-related issues such as: too cold, too warm, frost buildup, not running, or running too long. This is a genuine OEM part. It is recommended to disconnect the power to your appliance before starting your repair.