Vaillant · ecoTEC plus Boilers
The fan is not operating correctly, possibly due to loose connections, a blocked fan, a defective Hall sensor, or faulty electronics.
Click steps to track your progress.
Ensure the plug on the fan is correctly and securely plugged in.
Check the 24V DC between the red and blue wires on the fan (requires specialist tools).
Check the 6-15V DC between the grey and blue wires on the fan (requires specialist tools).
If voltages are fine, the fan itself is likely faulty and needs replacement (contact a technician).