Hi
When setting the blower fan to either demist the windscreen or to windscreen/top vents there is a loud squealling noise coming from the engine bay. If the blower directional setting is then moved to any of the other directions eg to feet only, the squealling stops. The noise does not vary with the fan speed setting and does not appear when the engine is not running.
I am somewhat baffled and any suggestions would be gratefully received.
Thanks