Error Code 15 — Communication fault between indoor and outdoor unit

What does 15 mean?

The outdoor unit control board cannot communicate with the indoor unit control board for an extended period. This prevents the system from operating.

• Bad communication wiring between units
• Loose connections on terminal blocks
• Faulty PCB on either unit
• Incomplete or inadequate ground connection

Click steps to track your progress.

1. 1

   Ensure the communication cable connections at the terminal blocks are tight and correct.

2. 2

   Verify that the communication cable (14/4 stranded copper) is properly connected to the correct terminals.

3. 3

   Check that there are no splices in the communication wire.

4. 4

   Ensure PCB connections at CN21 are in good order.

5. 5

   Check the ground connection for completeness and adequacy.