I have a 2000 A6 2.7T. When the aircon is on the fan nearest the front grill seems to make quit a noise. The bearings are ok and I cant see anything actually wrong with it except for seems to run really fast so it sounds like a jet. If the aircom is on its on. It slows down every now and then but before it stops moving its off again at high speed.
Is this normal on this model ?

 

Turn the vehicle off and attempt to turn the electric fan closest to the engine. Its the one on the passenger side of the vehicle. Ill bet youll find it wont turn. Theres a piece of rubber that falls in there and binds up the fan. Sometimes you can take the rubber piece out and all is well. Sometimes the fan and the fan control module get damaged and both must be replaced.

 

Thankyou Dankhound you were spot on with the rubber thing. I pulled a foot long piece of rubber out of the fan. It now spins freely.

 

nice to see a quick fix dank knows his job