Branch Box LED 402 blinks 5 times — Serial communication error with Indoor Unit A.

What does LED 402 (5) mean?

LED 402 flashes five times, indicating a serial communication error between the branch box and Indoor Unit A.

• Loose or incorrect wiring between the branch box and Indoor Unit A.
• Malfunctioning communication circuit in Indoor Unit A or the branch box.

Click steps to track your progress.

1. 1

   Reset the power to the branch box and Indoor Unit A by cycling their circuit breakers.

2. 2

   Check the communication wiring connections between the branch box and Indoor Unit A for any looseness or damage.

3. 3

   Ensure all connections are secure and properly seated.

4. 4

   If the error persists, professional service is needed to diagnose the communication line or units.