Hey,
I am having the strangest noise when my climate control is on "Auto." My audi sounds like a jet engine. The noise goes away when I disengage the climate control (turn it off) or leave it on Econ. Any ideas on what the problem is and if so is there an easy solution? (The noise doesn't bother me as I can't hear it in the car, but I scared the crap out of my kids the other day.) Any help is appreciated.
-Don

 

Outside the car? In the engine bay? Check your A/C compressor.

 

The noise is coming from the front of the engine compartment. I believe it might be a belt, but the german engineering scares the crap out of me.

 

Yep... sounds like either the belt or a/c clutch.. since it only happens in 'auto', I'd look at the a/c.

 

This noise isn't uncommon. I know I also have it in the summer when I'm running AC. It's technically not a mechanical issue other than an irritant, however. Dealerships say it is normal, but people claim that it's most likely the auxiliary fan going bad (maybe legit). I haven't heard of anyone fixing it by replacing the fan, though, so take what you can out of that. Do a search next time, too:
https://www.audiforums.com/forum/audi-a6-9/99-%5E-noisey-electric-fan-72113/

 

I had an issues when the air was running. the bracket holding the compressor to the engine block had a bad bolt. The missing bolt caused the bracket to break and cause an awful noise. Not sure if that is your issue or not.