Samsung Air Conditioner Error Code 231

Error code 231 on a Samsung air conditioner indicates a fault in the COND OUT (condenser outlet) main temperature sensor circuit. The control PCB monitors the voltage signal from this sensor continuously, and when the signal falls outside the acceptable operating window, the unit flags an error. Specifically, the fault triggers when the sensor circuit reads above 4.9V, which corresponds to an indicated temperature below -50 degrees Celsius, or below 0.4V, which corresponds to an indicated temperature above 93 degrees Celsius. Neither condition represents a realistic operating temperature, so the control board interprets either reading as a sensor or wiring fault rather than an actual thermal event.

The COND OUT temperature sensor is a negative temperature coefficient (NTC) thermistor positioned at the condenser outlet. As temperature rises, resistance falls, which causes the voltage signal sent to the PCB to drop proportionally. An open circuit in the sensor wiring causes the signal voltage to rail high (over 4.9V), mimicking an impossibly cold reading. A short circuit causes the voltage to collapse toward zero (below 0.4V), mimicking an impossibly hot reading. Both conditions prevent the unit from accurately monitoring refrigerant or coil temperatures at the condenser outlet, which is critical for capacity control and protection logic.

The most likely causes include a broken wire in the sensor harness, a corroded or unseated connector at either the sensor end or the PCB, a failed thermistor with an internal open or short, or physical damage to the sensor body from vibration or corrosion. The first diagnostic step is to inspect all wiring and connectors in the COND OUT sensor circuit before condemning the sensor itself, since connector issues are frequently the root cause.