Danfoss · VLT AutomationDrive FC 301/302
The drive's protective function has detected an issue with the internal fan, indicating it is not running or improperly mounted. For DC fans, this occurs if no feedback is received from its sensor when commanded to run. For AC fans, the voltage supply is monitored.
Click steps to track your progress.
Safely de-energize the drive and visually inspect the internal cooling fan blades for obstructions (e.g., dust buildup, foreign objects).
With power off, manually attempt to spin the fan blades to check for mechanical binding or seized bearings.
Verify the fan's electrical connection on the control board (e.g., J201) is securely seated.
Measure the voltage supplied to the fan terminals (e.g., +24VDC, GND) on the control board (e.g., J201 pins 1 and 2).
If the fan is a DC type, measure the feedback signal line (e.g., J201 pin 3) from the fan connector to the control board for pulse presence.