Kenmore Refrigerator Defrost Thermostat Replacement Guide

Kenmore Refrigerator Defrost Thermostat Replacement Guide — What This Part Does

The defrost thermostat (also called a bi-metal thermostat, termination thermostat, or defrost sensor) is a temperature-controlled switch mounted on the evaporator coil. It closes when the coil is cold and opens when the coil warms up during the defrost cycle. This switch monitors evaporator coil temperature and controls defrost termination so the heater energizes properly and shuts off at the right time.

When the thermostat fails, it may stick open, stick closed, or fail to switch at the correct temperature. The result is that the defrost system cannot terminate correctly. The heater may not turn on when needed or may not shut off at the proper coil temperature. This leads to frost and ice accumulation on the coils, improper cooling, and temperature control problems.

Jump to Replacement Steps

Signs It Needs Replacing

• Heavy frost or ice buildup on the evaporator coils Thick frost covering the coils in the freezer compartment indicates the defrost cycle is not completing because the thermostat is not signaling the heater to run or is not terminating the cycle correctly.
• Refrigerator or freezer running warmer than normal When frost blocks airflow over the evaporator, cooling performance drops and compartment temperatures rise above the setpoint.
• Compressor running constantly without cycling off The unit runs non-stop trying to reach temperature because the iced-over coils cannot transfer heat efficiently.
• No continuity at cold temperature or continuity at warm temperature during testing A properly working thermostat should be closed (continuity) at about 20°F and open (no continuity) at about 40°F, so any other reading confirms the switch has failed.
• Water pooling inside the refrigerator or freezer Excessive frost melting during off cycles or a clogged drain line (often found alongside thermostat failures) can cause water leaks inside the compartments.
• Defrost heater does not warm up during the defrost cycle If the thermostat is stuck open, the defrost heater circuit cannot complete and the heater will not energize to melt frost off the coils.

How to Replace It

1. Unplug the refrigerator from the wall outlet and shut off the water supply line if the unit has an ice maker or water dispenser.
2. Remove all freezer shelves, baskets, and the ice maker (if equipped) to access the rear freezer wall panel.
3. Remove the screws securing the evaporator cover panel on the back wall of the freezer and lift the panel out to expose the evaporator coil and defrost components.
4. Defrost any ice buildup on the coils and heater using a hair dryer or by letting the unit sit unplugged until all ice melts, then wipe up water and dry the area.
5. Locate the defrost thermostat clipped or mounted to the evaporator coil tubing (it is a small round or cylindrical component with two wire leads).
6. Test the old thermostat with a multimeter set to continuity or ohms: at room temperature (about 40°F) it should read open (no continuity), and when placed in ice water with salt (about 20°F) it should read closed (continuity). Replace the thermostat if it fails either test.
7. Disconnect the wire terminals or cut the wires if they are factory-spliced, then unclip or remove the old thermostat from the evaporator tubing.
8. Clip the new defrost thermostat onto the evaporator coil in the same position as the original, making sure the sensor bulb contacts the coil tubing for accurate temperature sensing.
9. Reconnect the wire terminals using the original plug connectors or join the wires with approved butt-splice crimp connectors if the original wires were cut.
10. Reinstall the evaporator cover panel and all screws, then replace the freezer shelves, baskets, and ice maker components.
11. Plug the refrigerator back in, turn on the water supply, and monitor the unit through the next defrost cycle to confirm proper operation and that frost no longer accumulates on the coils.

The Part You Need

Related Error Codes

If this part is failing you may also see one of these codes:

• Kenmore Refrigerator Er 1F error code
• Kenmore Refrigerator Er Dh error code
• Kenmore Refrigerator Er Ff error code

When to Call a Pro

Call a technician if you are not comfortable working inside the freezer compartment with the evaporator coil exposed, if you cannot safely defrost and dry the evaporator area, or if the refrigerator still does not defrost properly after replacing the thermostat. The defrost heater, defrost timer, or control board may also be faulty, and those components require additional testing and diagnosis. A pro can test the entire defrost system with a multimeter and verify the correct operation of the timer, heater, and thermostat together to pinpoint the actual failed part.