July 20, 2015

How to replace the defrost bi-metal thermostat in a top-freezer refrigerator

By Lyle Weischwill
How to replace the defrost bi-metal thermostat in a top-freezer refrigerator

This DIY repair guide gives step-by-step instructions on how to replace the defrost bi-metal thermostat in a top-freezer refrigerator. The defrost bi-metal thermostat shuts off the defrost heater if it gets hot enough to damage the evaporator. If the defrost bi-metal thermostat fails, the heating element doesn't turn on, and frost builds up on the evaporator. When the frost buildup is excessive, the refrigerator can't cool well. If the defrost bi-metal thermostat fails, replace it with a manufacturer-approved replacement part.

This basic repair procedure works for some Kenmore, Frigidaire, Whirlpool, KitchenAid, Maytag, Amana, GE, Samsung, Gibson, Crosley and Haier top-freezer refrigerators.

Quick links
Tools required
Wire cutter
Nut driver set
Wire stripper
Heat gun
Work gloves
Repair difficulty
Time required
15 minutes or less
Repair difficulty
Time required
15 minutes or less
How to replace a top-freezer refrigerator defrost bi-metal thermostat video.

Replacing a refrigerator bi-metal thermostat video.

Instructions

  1. 01.

    Shut off the power

    Move your frozen food from the freezer to the refrigerator section and then unplug the power cord from the wall outlet.

  2. 02.

    Remove the freezer shelf

    Remove the spacer in the freezer shelf.

    Push the shelf to the left to release the right side of the shelf from the holes.

    Pull the shelf out of the freezer.

    Remove the freezer shelf spacer.

    Remove the freezer shelf spacer.

    Remove the shelf.

    Remove the shelf.

  3. 03.

    Remove the evaporator cover

    Remove the mounting screws from the evaporator cover.

    Pull the top of the evaporator cover down and unplug the evaporator fan wire harness.

    Push the evaporator cover to the left side of the freezer and disconnect the green ground wire and the ice maker wire harness from the evaporator cover.

    Pull the evaporator cover out of the freezer.

    Remove the evaporator cover screws.

    Remove the evaporator cover screws.

    Pull down the top of the cover.

    Pull down the top of the cover.

    Unplug the evaporator fan wire harness.

    Unplug the evaporator fan wire harness.

    Push the evaporator cover to the side.

    Push the evaporator cover to the side.

    Disconnect the green wire.

    Disconnect the green wire.

    Disconnect the ice maker wire harness.

    Disconnect the ice maker wire harness.

  4. 04.

    Pull out the defrost bi-metal thermostat and freezer wire harness and freezer wire harness

    Unplug the wires from the defrost heater.

    Release the defrost bi-metal thermostat and the defrost thermistor from the evaporator coils.

    Unplug the freezer wire harness from the back wall and lay the freezer harness on a work table.

    Unplug the defrost heater wire harness.

    Unplug the defrost heater wire harness.

    Release the bi-metal thermostat.

    Release the bi-metal thermostat.

    Release the defrost thermistor.

    Release the defrost thermistor.

    Unplug the freezer wire harness.

    Unplug the freezer wire harness.

  5. 05.

    Remove the defrost bi-metal thermostat

    Cut the electrical wires close to the defrost  bi-metal thermostat.

    Remove the defrost bi-metal thermostat from the freezer wire harness.

    Cut the defrost bi-metal wires.

    Cut the defrost bi-metal wires.

  6. 06.

    Install the new defrost bi-metal thermostat

    Strip 1/4-inch of insulation from the ends of the supply wires and new defrost bi-metal thermostat wires.

    Slide the heat shrink tubes onto the new bi-metal thermostat wires.

    Connect the new bi-metal thermostat wires to the supply wires using the wire connectors.

    Slide the heat shrink tubes over the wire connectors.

    Heat the tubes using a heat gun to seal the connections.

    Tip: The defrost bi-metal kit includes the wire connectors and heat shrink tubes.

    Strip the wire ends.

    Strip the wire ends.

    Slide on the heat shrink tubes.

    Slide on the heat shrink tubes.

    Connect the bi-metal thermostat wires.

    Connect the bi-metal thermostat wires.

    Crimp the wire connectors.

    Crimp the wire connectors.

    Heat the shrink tubes.

    Heat the shrink tubes.

  7. 07.

    Reinstall the freezer wire harness

    Plug the freezer wire harness into the back wall receptacle.

    Attach the defrost bi-metal thermostat and defrost thermistor to the evaporator.

    Connect the wires to the defrost heater.

    Plue in the freezer wire harness.

    Plue in the freezer wire harness.

    Reinstall the defrost thermistor.

    Reinstall the defrost thermistor.

    Clip the new defrost bi-metal thermostat in place.

    Clip the new defrost bi-metal thermostat in place.

    Connect the defrost heater wire.

    Connect the defrost heater wire.

  8. 08.

    Reinstall the evaporator cover

    Position the evaporator cover in the freezer compartment and reconnect the ice maker wire harness and ground wire.

    Push the evaporator cover to the center of the freezer compartment and reconnect the evaporator fan wire harness.

    Position the evaporator cover over the evaporator and reinstall the mounting screws.

    Reattach the ice maker wire harness.

    Reattach the ice maker wire harness.

    Reattach the green wire.

    Reattach the green wire.

    Reconnect the evaporator fan wire harness.

    Reconnect the evaporator fan wire harness.

    Push the evaporator cover into place.

    Push the evaporator cover into place.

    Reinstall the evaporator cover screws.

    Reinstall the evaporator cover screws.

  9. 09.

    Reinstall the freezer shelf

    Push the shelf into the mounting holes on the left side of the freezer compartment wall.

    Slide the shelf to the right and reinstall the shelf spacer.

    Reinstall the freezer shelf.

    Reinstall the freezer shelf.

    Reinstall the shelf spacer.

    Reinstall the shelf spacer.

  10. 10.

    Restore power

    Plug in the refrigerator to restore power.

Warning: Undertaking repairs or maintenance to appliances or power equipment can be hazardous. Should you choose to undertake repairs or maintenance, you are assuming the risk of injury to your person or property. In an effort to reduce the risk, use the proper tools and safety equipment noted in the applicable 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 or maintenance, however, should only be performed by a qualified technician.

Symptoms common to all refrigerators

Choose a symptom to see related refrigerator repairs.

Main causes: leaky door gasket, defrost system failure, evaporator fan not running, dirty condenser coils, condenser fan not running
Main causes: blocked air vents, compressor problems, condenser or evaporator fan not working, control system failure, sensor problems
Main causes: water valve leaking, frozen or broken defrost drain tube, overflowing drain pan, cracked water system tubing, leaking door seal
Things to do: clean condenser coils, replace the water filter, clean the interior, adjust doors to prevent air leaks, clean the drain pan
Main causes: damaged door seal, faulty defrost sensor or bi-metal thermostat, broken defrost heater, bad defrost timer or control board
Main causes: blocked vents, defrost system problems, evaporator fan failure, dirty condenser coils, bad sensors, condenser fan not working
Main causes: jammed ice cubes, broken ice maker assembly, dirty water filter, kinked water line, bad water valve, freezer not cold enough
Main causes: control board or cold control failure, broken compressor start relay, compressor motor failure, defrost timer problems

Repair guides common to all refrigerators

These step-by-step repair guides will help you safely fix what’s broken on your refrigerator.

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If the temperature in your refrigerator doesn't match the temperature you set, the problem could be the temperature control board—a service technician can give you a definite diagnosis. If the board is at fault, follow these steps to replace it yourself.

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Use the advice and tips in these articles and videos to get the most out of your refrigerator.

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