Error Code: PC 40 – Communication Error Between Outdoor Main Chip and Compressor Drive Chip

Error Code: PC 40 – Communication Error Between Outdoor Main Chip and Compressor Drive Chip

What this means:
The outdoor main control board (PCB) is not receiving any signal from the compressor’s drive chip (IPM board). This usually points to a wiring issue, a faulty IPM board, or a defective main board.

Try this first (quick check):

1. Turn off power to the unit completely.

2. Wait 2 full minutes.

3. Turn it back on and see if the error clears.

• If the error is gone — the issue may have been temporary.

• If the error remains — continue with the steps below.

Next steps (for technicians):

1. Check the compressor drive chip (IPM board):

   • Confirm that at least one LED is on.

   • If not, check the signal wire connection between the IPM and main board.

2. Reconnect wiring if loose or disconnected, then power cycle and check again.

3. If the error persists:

   • Replace the compressor drive chip (IPM board).

   • If issue continues, replace the electric control box.

   • If still unresolved, replace the outdoor main PCB.

What you might need:

• Compressor drive chip (IPM board)

• Outdoor main PCB

• Electric control box

• Signal connection wires

Helpful tip:
A missing or weak signal between the compressor's control module and the main board will trigger this fault. Start by checking power and signal LEDs on the IPM before replacing parts.

Click here to view the detailed guide.TS31