0403 (Ed) Serial communication error

What does 0403 (Ed) mean?

This error indicates a problem with the serial communication within the outdoor unit. It can be caused by broken wires, poor connector contact, or malfunctions in the communication circuits on either the outdoor controller board or power board.

• Wire breakage or contact failure of connector CN2 or CN4.
• Malfunction of power board communication circuit on outdoor controller board.
• Malfunction of communication circuit on outdoor power board.

Click steps to track your progress.

1. 1

   Turn off the power to the outdoor unit at the circuit breaker.

2. 2

   Inspect the CN2 and CN4 connectors on the outdoor unit's circuit board for any signs of looseness or damage.

3. 3

   Visually check the wiring connected to CN2 and CN4 for any breaks or frayed insulation.

4. 4

   Ensure all connectors are firmly seated.

5. 5

   Restore power. If the error persists, professional diagnosis of the communication circuits may be necessary.