How to Fix / Troubleshooting

Safety first: Turn off power at the breaker before accessing the indoor coil.

Step 1 – Access evaporator coil: Remove the front cover and filters. On many Samsung wall units, the coil sensor is clipped to the evaporator fins near the center or side.
Step 2 – Check sensor position: Ensure the thermistor is firmly clipped to the coil surface; a loose sensor can misread temperature.
Step 3 – Inspect wiring: Follow the sensor wires back to the PCB and check for cuts, pinches, or loose connectors.
Step 4 – Replace sensor: If the sensor is damaged or readings are erratic (unit cycles incorrectly), replace with the correct Samsung evaporator thermistor.
Step 5 – If error persists: The indoor PCB sensor circuit may be defective and should be tested/replaced by a technician.

Indoor unit shows E122; unit may not respond to temperature changes.

Possible Causes