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 replacement part.
This basic procedure can help you replace the defrost thermistor in some Kenmore, Frigidaire, Electrolux, LG and Samsung top-freezer refrigerators.
Replacing a refrigerator defrost thermistor video.
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.
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 shelf.
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.
Remove the evaporator cover screws.
Pull down the top of the cover.
Disconnect the wire harness.
Push the evaporator cover to the side.
Disconnect the green wire.
Disconnect the ice maker wire harness.
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.
Unplug the defrost heater wire harness.
Release the bi-metal thermostat.
Release the defrost thermistor.
Unplug the freezer wire harness.
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.
Plug in the new freezer wire harness.
Clip the defrost thermistor in place.
Clip the defrost bi-metal in place.
Plug in the defrost heater wire.
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 green wire.
Reconnect the evaporator fan wire harness.
Push the evaporator cover into place.
Reinstall the evaporator cover screws.
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 shelf spacer.
Restore electrical power
Plug in the refrigerator to restore power.
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