Samsung Air Conditioner Error Code 122

Error code 122 on a Samsung air conditioner indicates a fault with the indoor unit heat exchanger IN (inlet) temperature sensor. This thermistor is mounted on the indoor heat exchanger coil and continuously reports coil temperature data to the control board. The board uses this data to regulate refrigerant flow, compressor operation, and prevent freeze-up or overheating conditions. When the signal from this sensor falls outside the expected resistance range, either reading as an open circuit or a short circuit, the system flags error 122 and halts normal operation to prevent equipment damage.

The three primary hardware faults that trigger this code are connector dislocation, wire breakage, and a defective sensor. A dislodged connector at either the sensor end or the control board header is the most frequent culprit, often caused by vibration over time or improper reassembly after prior service. Wire breakage can occur anywhere along the sensor harness, particularly at stress points near clips or routing guides. A failed thermistor itself will read either infinite resistance (open) or near-zero resistance (short), both of which fall well outside the normal operating range the control board expects.

Diagnosing this fault begins with a visual inspection of the sensor wire for any obvious breaks, chafing, or pinching, followed by checking that the connector is fully seated at both ends. If the wiring appears intact, the thermistor should be tested with a multimeter. A properly functioning NTC thermistor will show measurable resistance that changes with temperature. A reading of zero ohms or infinite resistance at ambient temperature confirms a failed sensor requiring replacement.