Error 0403 - Serial communication error (Control board to INV board).

What does 0403 mean?

This error indicates a serial communication failure between the main control board and the inverter (INV) board, specifically identified by detail code 01. This disrupts critical communication needed for compressor operation.

• Faulty wiring connections between the Control board and the INV board
• Failure of either the INV board or the Control board

Click steps to track your progress.

1. 1

   Carefully inspect all wiring connections between the main Control board and the Inverter (INV) board.

2. 2

   Ensure that connectors (such as CN2 and CN4) are fully and securely seated on both boards.

3. 3

   Check for any visible damage, pinching, or wear on the communication wires themselves.

4. 4

   If the error persists, especially if the unit tries to power on automatically after a reset, it suggests a potential failure in either the INV board or the Control board.

5. 5

   A qualified technician should diagnose the specific board failure and perform any necessary replacements.