LG Refrigerator Error Code R-area defroster sensor open/short

The R-area defroster sensor open/short error indicates a fault in the refrigerator compartment evaporator defrost sensor circuit. This sensor monitors the temperature of the evaporator coil in the refrigerator section to control the defrost cycle, ensuring ice buildup is melted at the right intervals without over-defrosting. The control board triggers this error when the sensor reports a temperature reading outside the valid range, specifically below -50°C or above +50°C. These extreme out-of-range readings tell the board that the sensor is either disconnected (open circuit) or has a short circuit rather than returning a legitimate temperature value.

The defrost sensor is a negative temperature coefficient (NTC) thermistor, meaning its resistance decreases as temperature rises. A properly functioning sensor will have a predictable resistance value at any given temperature. An open circuit, often caused by a broken wire or failed sensor element, will drive the resistance to infinity, which the board interprets as a temperature below -50°C. A short circuit drives resistance toward zero, which registers as a temperature above +50°C. Either condition disables the automatic defrost system and can eventually lead to heavy frost accumulation on the evaporator coil, reduced cooling performance, and potential food spoilage.

Diagnosis involves disconnecting the sensor connector and measuring resistance across the sensor terminals with a multimeter. A shorted sensor will read near zero ohms, while an open sensor will show no continuity. Wiring between the sensor and the control board should also be inspected for damage, pinching, or corroded connector pins. If wiring checks out, the sensor itself is the most likely failed component and should be replaced.