51 — Out-of-step detection

What does 51 mean?

This fault indicates that the system has detected an out-of-step condition. This could be due to loose wiring, a faulty control board, fan motor starting issues, demagnetization, or poor fan motor insulation.

• Loose wire connection
• Defective control board components
• Fan motor starting overload
• Fan motor demagnetization
• Fan motor insulation failure

Click steps to track your progress.

1. 1

   Check the fan motor wire connections.

2. 2

   Replace the control board.

3. 3

   Replace the fan motor.