C121 - Indoor room temperature sensor error

What does C121 mean?

The indoor unit displays C121, indicating a problem with the indoor room temperature sensor. This means the unit cannot accurately measure the room temperature.

• Indoor unit temperature sensor is not connected correctly
• Sensor is improperly placed
• Faulty sensor
• Faulty indoor unit main board (PBA)

Click steps to track your progress.

1. 1

   Turn off the air conditioner at the main power supply.

2. 2

   Ensure the indoor unit's temperature sensor is securely connected.

3. 3

   Verify the sensor is positioned correctly and not obstructed.

4. 4

   If the error persists, contact a service technician to check the sensor resistance or replace the indoor PBA.