





Evaporator coils frost over completely because the defrost heater never activates — the failed thermostat breaks the heating circuit even when coils are below 30°F.
Blocked airflow from frost-packed evaporator coils prevents cold air reaching the fresh food compartment, causing both sections to warm up.
With no effective defrost cycle, the compressor runs non-stop trying to overcome rising temperatures, shortening its lifespan and increasing energy bills.
When a defrost thermostat fails intermittently, frost melts unevenly and overflows the drain pan, causing water to pool or drip inside the refrigerator compartment.





💡 Pro Tip: How to Know If Your Defrost Thermostat Has Failed
Your part is likely the culprit if you notice any of the following:
⚠️ Excessive frost or ice buildup on the freezer evaporator coils behind the back wall panel
⚠️ Freezer and/or refrigerator compartment running warmer than normal despite compressor running
⚠️ Refrigerator runs continuously without cycling off — compressor never rests
⚠️ Water pooling or dripping inside the fridge compartment from melting frost overflow
🔍 DIY Test: Remove the freezer back panel and clip your multimeter leads to the thermostat terminals. At room temperature it must show continuity (closed). If it reads open (infinite resistance) at room temp, the thermostat has failed and needs replacement. Always test the defrost heater (WR51X10055) at the same time — both parts fail together in many cases.
📦 What's in the Box
✅ 1× Defrost Thermostat WR50X10065 (L140-30F, bi-metal, tube-mount, plastic housing, orange 4-3/4" lead + yellow 15-1/2" lead)
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Disclaimer: Compatibility information, part numbers, and model fitment data on this page are sourced from manufacturer databases and third-party references. While we strive for accuracy, please verify your appliance model number before ordering. Heima is not responsible for errors or omissions in compatibility listings.
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