A refrigerator's automatic defrost system has three components: the defrost timer or adaptive defrost control board that starts each defrost cycle, the defrost heater that generates heat to melt frost off the evaporator coils, and the defrost thermostat that shuts the heater off when the job is done. The WPW10165425 is the genuine OEM thermostat in this system — manufactured by Whirlpool and used across their full range of brands including Kenmore, KitchenAid, Maytag, and Amana. It clips onto the evaporator tubing inside the freezer and monitors coil temperature during each defrost cycle, opening the heater circuit at approximately 42°F to prevent the freezer from overheating.
When any one of the three defrost components fails, the symptom looks the same at first — frost builds on the evaporator and the refrigerator warms up. But the diagnostic path is different for each. A failed thermostat shows no continuity at room temperature. A failed heater also shows no continuity but at any temperature. A failed timer or control board will show good continuity on both the thermostat and heater but the defrost cycle never initiates. Checking all three in order — thermostat, then heater, then timer — is the fastest way to isolate which part has failed and avoid replacing parts that are still good.
Will This Fix Your Refrigerator?
Replace this thermostat if the evaporator coils are iced over and the thermostat reads open (no continuity) at room temperature. Part Number: WPW10165425 — genuine OEM Whirlpool defrost thermostat. Diagnostic order: test thermostat first, then heater, then timer/control board.
Common Symptoms This Part Fixes
Evaporator coils packed with frost from top to bottom
Fresh food compartment running warm while the compressor cycles normally
Refrigerator running nonstop without reaching the set temperature
Defrost heater does not activate during the defrost cycle
Thick ice sheet on the back wall inside the freezer
Little or no cold airflow from the freezer vents into the fridge section
Fits side-by-side, top-freezer, and bottom-freezer refrigerators built by Whirlpool and sold under any of the brands above. Whirlpool manufactures appliances for all of these brand names using shared components, so the same thermostat fits across the full range. Kenmore models built by Whirlpool typically have model numbers starting with 106. Always verify your specific model number before ordering.
Key Features
Genuine OEM Whirlpool defrost thermostat — factory original part
Bimetal type — clips directly onto the evaporator tubing
L42-30F temperature rating — opens at ~42°F, closes at ~30°F
5-1/4" orange wire and 25" brown wire with 1/2" mounting clip
Shuts off the defrost heater at the correct temperature to prevent freezer overheating
Installation approximately 1–2 hours with nutdriver and screwdrivers
Unplug the refrigerator before starting this repair. The thermostat is located on the evaporator coils behind the back panel inside the freezer. Remove all food and shelves, then remove the screws holding the back panel. If ice is holding the panel in place, let it melt naturally or use a hair dryer on low heat — do not use a sharp tool to chip ice off the evaporator coils, as puncturing a tube destroys the sealed refrigerant system. Disconnect the wire leads from the old thermostat, release the clip from the evaporator tubing, and remove it. Clip the new thermostat onto the same tube in the same position and reconnect both wires. Reassemble the back panel, restore power, and let the refrigerator run through a complete defrost cycle to confirm the heater activates and shuts off as expected.
Frequently Asked Questions
How do I tell which defrost component has failed — thermostat, heater, or timer?
Unplug the refrigerator and access the evaporator behind the freezer back panel. Test the thermostat first — at room temperature it should show continuity. If it reads open, the thermostat is the failed part. If the thermostat tests good, check the defrost heater for continuity (typically 20–40 ohms). If the heater reads open, replace the heater. If both test good, the defrost timer or adaptive defrost control board is not initiating the cycle and should be checked or replaced.
My refrigerator has an adaptive defrost control board instead of a mechanical timer. Does this thermostat still apply?
Yes. The thermostat is a separate component from the defrost timer or control board. Whether your refrigerator uses a mechanical timer that runs the defrost cycle on a fixed schedule or an adaptive defrost control board that varies the cycle based on usage patterns, the thermostat does the same job in both — it clips onto the evaporator and shuts off the heater when the coils reach the cutoff temperature. The same thermostat works with either system.
Can I advance the defrost timer manually to test the defrost system?
On refrigerators with a mechanical defrost timer, yes. The timer usually has a small slot or notch that can be turned with a flathead screwdriver to manually advance it into the defrost cycle. If the heater turns on when you advance the timer, the timer itself may be failing to advance on its own. On models with an adaptive defrost control board, there is no manual advance — you would need to test the board's output with a multimeter or replace it to rule it out.
Is WPW10165425 the same as W10165425?
Yes. Whirlpool added the WP prefix to many of their part numbers in a numbering update. WPW10165425 is the current number and W10165425 is the earlier version — they refer to the identical thermostat. If your parts diagram or old thermostat shows either number, this is the correct replacement.
How often does a defrost thermostat need to be replaced?
There is no scheduled replacement interval. The bimetal disc inside the thermostat is a mechanical component that wears over time as it flexes through thousands of defrost cycles. Most thermostats last 10–15 years or more, but they can fail sooner. Replace it only when it tests open at room temperature or the refrigerator shows symptoms of a defrost failure.
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