F155 fault in WEG CFW900 Drive indicates a Control Internal Air Overtemperature. This means the control circuit area overheated and the drive tripped to prevent hardware damage.
Cause:
Control circuit overtemperature fault.
- High ambient temperature around the inverter (>50 °C) and high output current.
- Locked or defective fan.
- Inverter heat sink too dirty.
Remedy:
Check cooling fan, clean heatsink, and reduce ambient/room temperatures if too high.
