Samsung Air Conditioner Error Code E122

The Samsung E122 error code indicates a fault in the indoor heat exchanger evaporator inlet (EVAP IN) temperature sensor circuit. This sensor monitors the refrigerant temperature at the inlet side of the indoor coil and feeds that data to the control board, which uses it to regulate compressor operation, fan speed, and refrigeration cycle timing. When the control board detects a signal outside the expected resistance or voltage range, either an open circuit (infinite resistance from a broken wire) or a short circuit (near-zero resistance from insulation failure or connector bridging), it triggers the E122 fault and halts normal operation to prevent equipment damage.

The three primary root causes listed for this code are connector dislocation, wire breakage, and a defective sensor. Connector dislocation is the most common culprit and occurs when the sensor harness plug separates from its mating connector on the control board or sensor body, often due to vibration over time or improper handling during a previous service visit. Wire breakage typically results from chafing against sharp metal edges inside the indoor unit, repeated flexing near a connector crimp, or rodent damage. A defective sensor itself has failed internally, producing an out-of-range resistance reading even when the wiring and connections are intact.

The first diagnostic step is to inspect the in-temperature sensor wiring harness on the indoor heat exchanger for any visible signs of breakage, pinching, or abrasion, and then check that all connectors are fully seated. If the wiring appears intact, the sensor resistance should be measured at the connector and compared against the specification values from the unit's wiring diagram. A properly functioning NTC thermistor will show a predictable resistance curve relative to ambient temperature. Readings that are open (OL on a multimeter) or near zero ohms confirm wire failure or sensor failure, respectively.