My 914 -72 fresh air fan has a quite high sound level, it hums and snarls at all speeds but most on high speed of course. Some vibrations can also be felt inside the car.
Have checked the fan bearings for play (which seemed close to 0) and also lubricated them.The fan wheel balancing weights seems to be in place.

The noise is far better when the fan assembly is on the bench, guess the car body acts as a megaphone.

What noise level should I expect from an OK fresh air fan?


/Lars S

I don't find the fresh air fan to be terribly loud. The plastic of the fan is often brittle and can break between the blades and the top ring. These cracks can cause imbalances, or slight rubbings that can increase the volume. It sounds like you've had it apart already, so I'm guessing the usual leaves and detritus has been cleaned out.

My fan noise levels:
Low: Barely hear with engine off
Med: Barely hear at idle
High: Noticable when driving if radio is off.

It's been said a 911 fresh air blower was a better unit ?? Anything to this ?

IIRC, the 914 and 911 fans are the same units.

The Cap'n

Thanks everyone, I will take it apart once again and examine the fan wheel....

What years should the 911 fan fit the 914? (exept for 70-75 of course)


/Lars S

....Turn the stereo up!!....it is what it is.
(maybe cause I don't use it!!)

Problem solved!
The fan bearing holders (in felt/rubber) had become very sloppy making the rotor fall down to a position where the fan wheel could touch the ring and also the collector end rested on the lower bearing.
Replaced both holders with O-rings and the noise is gone!

Before


after




/Lars S