The WG03F01804 is a genuine OEM refrigerator defrost thermostat for GE and affiliated brand refrigerators and freezers. This defrost thermostat is a critical safety component that protects the refrigerator from overheating during the defrost cycle by automatically shutting off the defrost heating element if the evaporator coil temperature exceeds a safe maximum limit (typically -10°F to 0°F). The thermostat is constructed from durable metal housing with internal bimetallic strip technology that responds to temperature changes. The bimetallic strip bends when exposed to excessive heat, opening the electrical circuit and cutting power to the defrost heater. The WG03F01804 is designed specifically for refrigerator and freezer defrost circuits and works in conjunction with the main defrost timer or control board (which initiates the defrost cycle). The thermostat features two wire terminals for electrical connection and is mounted directly on the evaporator coil or in the freezer cavity near the evaporator. The thermostat is normally closed at room temperature (continuity present) and opens when the evaporator coil temperature exceeds the setpoint (typically around -10°F), stopping the defrost heater. The WG03F01804 replaces older part numbers including WG03F01818, WR50X10108, WR50X10109, 3033062, AP5712605, and EAP8688283 with improved reliability and consistency. Over time, refrigerator defrost thermostats can fail due to repeated thermal cycling causing metal fatigue, bimetallic strip corrosion or oxidation, electrical contact wear or burning, frost or ice buildup preventing proper temperature sensing, manufacturing defects, or moisture exposure. When the defrost thermostat fails, symptoms include the refrigerator not defrosting properly (ice buildup on evaporator coil), the defrost heater running continuously without stopping, the refrigerator not cooling (if the defrost heater is stuck on), frost or ice accumulating excessively on the evaporator coil, the refrigerator temperature rising above normal, water leaking inside the refrigerator from excessive ice melt, the freezer section becoming warmer than normal, or error codes displayed on the control panel (such as defrost error codes). The WG03F01804 is a complete replacement defrost thermostat that restores full refrigerator defrost cycle operation and safety protection. Replacing a faulty defrost thermostat eliminates all thermostat-related problems and restores reliable, safe refrigerator operation. Important: Always turn off power at the circuit breaker before working on the refrigerator. The defrost thermostat is a safety-critical component—never bypass or disable it. This part is a one-time-use component that cannot be reset or repaired; replacement is the only solution. Verify your refrigerator model number before ordering.