Serial Communication Error

What does Ed mean?

This error indicates a failure in serial communication, affecting either the link between the outdoor controller circuit board and the outdoor power circuit board, or the M-NET board. Common causes include wire breaks, loose connector contacts, or defective communication circuits on the involved boards. Without proper communication, the system cannot be controlled or monitored effectively, leading to operational failure or incorrect responses.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Review the M-NET transmission wiring method to ensure it's correctly installed and free from external noise interference.

2. 4

   If physical connections and wiring are sound, replace the outdoor power circuit board.

3. 5

   If the issue persists, replace the outdoor controller circuit board.