July 20, 2015

How to replace the defrost thermistor in a top-freezer refrigerator

How to replace the defrost thermistor in a top-freezer refrigerator

This DIY repair guide gives instructions for replacing the defrost thermistor in a top-freezer refrigerator. Attached to the evaporator, the defrost thermistor detects the evaporator temperature and sends temperature signals to the electronic control board. The electronic control board uses the defrost thermistor signals to control the defrost heater during the automatic defrost cycle. If the defrost thermistor fails, the control board won't control the defrost heater correctly, causing cooling problems in the refrigerator. If the defrost thermistor isn't working, replace it with the manufacturer-approved refrigerator part.

This basic procedure can help you replace the defrost thermistor in some Kenmore, Frigidaire, Electrolux, LG and Samsung top-freezer refrigerators.

Quick links
Tools required
Work gloves
Nut driver set
Repair difficulty
Time required
15 minutes or less
Repair difficulty
Time required
15 minutes or less
How to replace a defrost thermistor in a top-freezer refrigerator repair guide video.

Replacing a refrigerator defrost thermistor video.

Instructions

  1. 01.

    Shut off the power

    Unplug the power cord from the wall outlet. Move your frozen food from the freezer to the refrigerator section during this repair. 

  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.

    PHOTO: Remove the freezer shelf spacer.

    PHOTO: Remove the freezer shelf spacer.

    PHOTO: Remove the shelf.

    PHOTO: Remove the shelf.

  3. 03.

    Remove the evaporator panel

    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.

    PHOTO: Remove the evaporator cover screws.

    PHOTO: Remove the evaporator cover screws.

    PHOTO: Pull down the top of the cover.

    PHOTO: Pull down the top of the cover.

    PHOTO: Disconnect the wire harness.

    PHOTO: Disconnect the wire harness.

    PHOTO: Push the evaporator cover to the side.

    PHOTO: Push the evaporator cover to the side.

    PHOTO: Disconnect the green wire.

    PHOTO: Disconnect the green wire.

    PHOTO: Disconnect the ice maker wire harness.

    PHOTO: Disconnect the ice maker wire harness.

  4. 04.

    Remove the freezer harness

    Note: The defrost thermistor is a component of the freezer harness in this refrigerator.

    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 remove it.

    PHOTO: Unplug the defrost heater wire harness.

    PHOTO: Unplug the defrost heater wire harness.

    PHOTO: Release the bi-metal thermostat.

    PHOTO: Release the bi-metal thermostat.

    PHOTO: Release the defrost thermistor.

    PHOTO: Release the defrost thermistor.

    PHOTO: Unplug the freezer wire harness.

    PHOTO: Unplug the freezer wire harness.

  5. 05.

    Install the new freezer wire harness

    Plug the new 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.

    PHOTO: Plug in the new freezer wire harness.

    PHOTO: Plug in the new freezer wire harness.

    PHOTO: Clip the defrost thermistor in place.

    PHOTO: Clip the defrost thermistor in place.

    PHOTO: Clip the defrost bi-metal in place.

    PHOTO: Clip the defrost bi-metal in place.

    PHOTO: Plug in the defrost heater wire.

    PHOTO: Plug in the defrost heater wire.

  6. 06.

    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.

    PHOTO: Reattach the ice maker wire harness.

    PHOTO: Reattach the ice maker wire harness.

    PHOTO: Reattach the green wire.

    PHOTO: Reattach the green wire.

    PHOTO: Reconnect the evaporator fan wire harness.

    PHOTO: Reconnect the evaporator fan wire harness.

    PHOTO: Push the evaporator cover into place.

    PHOTO: Push the evaporator cover into place.

    PHOTO: Reinstall the evaporator cover screws.

    PHOTO: Reinstall the evaporator cover screws.

  7. 07.

    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.

    PHOTO: Reinstall the freezer shelf.

    PHOTO: Reinstall the freezer shelf.

    PHOTO: Reinstall the shelf spacer.

    PHOTO: Reinstall the shelf spacer.

  8. 08.

    Restore electrical 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.

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