Fault code 81 — Indoor ambient Temperature Sensor Fault

What does 81 mean?

The temperature sensor measuring the indoor ambient temperature is faulty. This could be due to connection issues, a defective sensor, or a problem with the controller board.

• Disconnection or contact failure of connectors on the outdoor controller circuit board
• Defective thermistor
• Defective outdoor controller circuit board

Click steps to track your progress.

1. 1

   Check the connection of the sensor's connector on the indoor controller circuit board.

2. 2

   Test the resistance of the thermistor or replace the temperature sensor.

3. 3

   If the sensor and connections are fine, replace the outdoor controller circuit board.