Refrigerator Not Defrosting? Defrost Thermostat Kit 5303918851 — Fix Frost Buildup Fast
A refrigerator that won't defrost isn't a compressor problem — it's almost always a failed defrost thermostat. In most Frigidaire and Electrolux refrigerators, the defrost thermostat is the safety cutoff that tells the defrost heater when to turn on and off. When it fails open, the heater never activates and frost accumulates on the evaporator coils until airflow is completely blocked. When it fails closed, the heater runs continuously and can damage the coils. ⚡ One of the most common defrost system failures in Frigidaire-platform refrigerators. Part 5303918851 is the genuine OEM defrost thermostat kit that restores proper defrost cycle control and eliminates runaway frost buildup.
❓ Is This the Right Part?
This is the correct fix if ALL of the following are true:
- ✔ Refrigerator powers on and compressor runs normally
- ✔ Freezer gets cold but frost is building up heavily on the back wall or coils
- ✔ Defrost heater confirmed functional (or not yet tested)
- ✔ ONLY problem is frost accumulation and the fridge not completing defrost cycles
Not sure? Send us your model number — we'll confirm before you order.
🔧 Common Symptoms
- Heavy frost or ice buildup on evaporator coils or freezer back wall
- Refrigerator section warming up while freezer stays cold
- Evaporator fan running but little to no airflow reaching the fridge compartment
- Defrost cycle never completing — frost never clears between cycles
- Compressor running constantly without reaching set temperature
- Clicking or cycling sounds as system tries to initiate defrost
✔ If these symptoms match, this is the most likely failed component in the defrost system.
✔ In most cases, replacing this defrost thermostat kit restores normal defrost operation immediately.
📦 Part Details
- Part Number: 5303918851
- Type: Defrost Thermostat Kit
- Brands: Frigidaire, Electrolux, Kenmore
- Condition: New Genuine OEM
- Ships From: Canada
The defrost thermostat rarely fails alone — if your defrost heater hasn't been tested, replace it at the same time. A failed heater with a new thermostat will produce identical symptoms within days. Testing or replacing both components in one service call eliminates the most common cause of repeat defrost failures on Frigidaire-platform refrigerators.
⚙️ Installation
Skill Level: Easy — 20–40 minutes. Disconnect power before servicing. Remove freezer shelves and the evaporator cover panel to access the coils. Locate the defrost thermostat clipped to the evaporator coil, disconnect the wire leads, and swap the thermostat. Reinstall the cover panel and shelves, restore power, and allow one full defrost cycle to confirm normal operation.
✓ Compatible Models
Confirmed compatible with select Frigidaire, Electrolux, and Kenmore refrigerator models. Contact us to verify your model number before ordering — defrost thermostat specifications vary by model and must be confirmed against your full model number on the door jamb sticker.
💡 Pro Tip
Before installing the new thermostat, manually defrost the evaporator coils completely. Installing a new thermostat over a heavily frosted coil means the first defrost cycle has to work overtime — and if the heater is marginal, it may not clear the ice load. A clean, frost-free coil surface gives the new thermostat the best chance of restoring normal cycle timing immediately.
✓ Model-Specific Repair Pages
✅Compatibility & Cross Reference
Not sure about your model number? Call 1-877-899-7278 and we’ll help you confirm. All brand names are the property of their respective owners and are used for compatibility reference only.
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