Perm. com. error additive with shunt — Permanent communication fault with accessory card

What does 77 mean?

There is a permanent communication fault with the accessory card for an additive with shunt. This prevents proper communication and blocks the accessory.

• Communication cables to the accessory card are incorrect or incorrectly installed.
• Fault in the communication circuits within the accessory, input, or display card.
• Incorrect address set on the accessory's dipswitch.
• The accessory card itself may be faulty.

Click steps to track your progress.

1. 1

   Turn off the Heat Pump at the main power supply.

2. 2

   Check all communication cables connected to the accessory card for additive with shunt for secure and correct connections.

3. 3

   If applicable, verify the dipswitch settings on the accessory card match the system configuration.

4. 4

   Restore power to the Heat Pump and check if the alarm has cleared.

5. 5

   If the problem persists, contact a qualified NIBE service technician for diagnosis.