Whirlpool Refrigerator Bimetal Defrost Thermostat Parts — Models & Compatibility

If you're dealing with frost buildup in your freezer or finding your ice cream suspiciously soft, there's a good chance your Whirlpool's bimetal defrost thermostat has failed. This small component controls when your refrigerator exits its defrost cycle — when it stops working, ice accumulates on the evaporator coils and temperatures go haywire. The WPW10225581 defrost thermostat works across Whirlpool, Maytag, KitchenAid, Kenmore, and Amana models, replacing the older W10225581 and several other part numbers.

Is This the Right Part for Your Model?

Check your refrigerator's model number — it's usually on a sticker inside the fridge compartment (along the left or right wall) or inside the freezer. Match it against the compatibility list below. This thermostat fits both side-by-side and top-freezer configurations, but the exact placement varies by series. The WRS series uses a different mounting clip than the ED series, so pay attention during removal.

About This Replacement Part

The bimetal defrost thermostat is a temperature-sensitive switch mounted on the evaporator coils. When the coils reach a specific temperature during defrost (usually around 60°F), the bi-metal disc snaps and breaks the circuit, ending the defrost cycle. Over time, this disc loses its spring tension or corrodes, causing it to stick open or closed. If it sticks closed, your freezer runs too cold and frost builds up endlessly. If it sticks open, the defrost heater never turns off properly, and your freezer section gets too warm — exactly what one owner described as "temperature control often unstable leading to warm food and freezer items."

Common Failure Symptoms

You'll know this part's failed when your fridge exhibits specific behaviors. Frost buildup is the most obvious — thick ice layers form on the back wall of the freezer, sometimes blocking vents entirely. Your freezer might run warmer than usual, or paradoxically, your fridge section might get too cold because the thermostat's stuck in defrost mode. Some units leak water onto the floor as accumulated frost melts faster than the drain pan can handle. In severe cases, the compressor runs constantly trying to compensate, driving up your electric bill noticeably.

What You'll Need for Installation

This is a moderate-difficulty repair that takes 30-60 minutes. You'll need a Phillips and flathead screwdriver to remove freezer panels — most Whirlpool models have 4-6 screws holding the rear panel in place. The actual thermostat replacement involves cutting the old wires (they're crimped, not connectorized) and splicing in the new unit using the included wire nuts. Some techs prefer heat-shrink tubing for a cleaner connection, but the wire nuts work fine. Unplug the fridge before you start, and give the freezer 20 minutes to warm up slightly so the panels aren't frozen in place.

Step-by-Step Replacement Process

Start by removing all freezer shelving and the rear panel covering the evaporator coils. You'll see the old thermostat clipped to the coil tubing — it's a small metal cylinder about the size of your thumb. Cut the wires about 2 inches from the old thermostat body (gives you working room). Strip 1/4 inch of insulation from each wire end, then twist the corresponding wires from your new WPW10225581 together. Secure with wire nuts, tug-test each connection, then clip the new thermostat body back onto the coil tube in the same position. Replace the panel and shelving, plug the fridge back in, and let it run for 24 hours before loading it fully. The unit should cycle normally — you'll hear the compressor kick on and off rather than running continuously.

Compatible Whirlpool Refrigerator Models

This defrost thermostat works across multiple Whirlpool families, including French door, side-by-side, and top-freezer configurations. Below are confirmed compatible models — if yours isn't listed but uses the original W10225581 or AP6017375 part number, this replacement will work.