CPU (green) LED not lit - CPU without power

What does CPU LED off mean?

The green CPU LED on the base board (AA2) is off, indicating that the central processing unit (CPU) is not receiving power or is not active. This prevents the Heat Pump's control functions from operating.

• CPU is without power.
• Internal fault on the base board.

Click steps to track your progress.

1. 1

   Ensure the main PWR LED is continuously lit (indicating base board power). If not, troubleshoot the PWR LED first.

2. 2

   Turn off the Heat Pump at the main power switch for a few minutes, then turn it back on to attempt a system reset.

3. 3

   If the CPU LED remains off, contact a qualified NIBE service technician to inspect the base board.