Inverter to Outdoor PCB Transmission Error

What does E45 mean?

A communication error has occurred between the inverter and the outdoor unit PCB, possibly due to a loose connection at the Cn1 terminal. This disrupts the control of the compressor by the inverter.

• Communication failure between the inverter's main PCB and the outdoor unit's control PCB.
• Loose or damaged communication wiring (e.g., terminal blocks P1-P5).
• Faulty main PCB on either the inverter or outdoor unit.

Click steps to track your progress.

1. 1

   Inspect the Cn1 connector on both the outdoor unit PCB and the inverter board — verify it is securely seated.

2. 2

   Check the continuity and integrity of the wiring connected to Cn1 using a multimeter.

3. 3

   Verify stable power supply to both the inverter board and the outdoor unit PCB.