How to Replace a Freezer Defrost Thermostat



This DIY repair guide explains how to replace the defrost thermostat in an upright freezer. The defrost thermostat, also called a bi-metal, protects the evaporator by turning the defrost heater off if the heater gets too hot. If the defrost thermostat stops working, frost forms on the evaporator fins, and the temperature in the freezer rises. Replace the defrost thermostat with the manufacturer-approved replacement part if it's no longer working.

Repair difficulty:
Time required:

Less than 45 min.

Parts Required

  • Defrost Bi-metal Thermostat

For manuals, repair guides, and specific part recommendations, enter your model number.

Tools Required

  • Phillips screwdriver
  • Work gloves

Before you begin

Wear work gloves to protect your hands.


 Warning: Undertaking repairs to appliances can be hazardous. Use the proper tools and safety equipment noted in the guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs should only be performed by a qualified technician.

How to Replace a Freezer Defrost Bi-metal Thermostat

Step 1: Disconnect the electrical power

Unplug the freezer or shut off the circuit breaker for the freezer.

Step 2: Remove the evaporator cover

Remove the drawers and shelves from the freezer.

Remove the screws from the evaporator cover at the back of the freezer.

Pull the evaporator cover out of the freezer.

Step 3: Remove the defrost bi-metal thermostat

Unplug the defrost bi-metal thermostat wires.

Unclip the defrost bi-metal thermostat and remove it.

 Hazard: The aluminum fins of the evaporator are sharp. Wear work gloves to protect your hands.

Step 4: Install the new defrost bi-metal thermostat

Clip the new defrost bi-metal thermostat onto the evaporator.

Connect the defrost bi-metal thermostat wires.

Step 5: Reinstall the evaporator cover

Position the evaporator cover on the back wall and reinstall the mounting screws.

Reinstall the evaporator cover gasket.

Reinstall the drawers and shelves inside the freezer cabinet.

Step 6: Restore electrical power

Plug in the freezer or turn on the house circuit breaker to restore power.