Alarm 331 - Overheated inverter (Persistent)

What does 331 mean?

The inverter has temporarily reached its maximum working temperature 3 times within 2 hours or continuously for 1 hour, indicating persistent overheating.

• Low supply voltage to the inverter.
• Poor cooling of the inverter (e.g., blocked airflow, high ambient temperature).
• Internal fault in the inverter.

Click steps to track your progress.

1. 1

   Ensure that the area around the Heat Pump's inverter compartment has adequate ventilation and is not obstructed.

2. 2

   Check that the outdoor ambient temperature is within the Heat Pump's specified operating range.

3. 3

   Turn off the Heat Pump at the main power switch for at least 15-30 minutes to allow the inverter to cool down completely, then restart.

4. 4

   If the problem recurs, contact a qualified NIBE service technician to inspect connections and cooling.