dcquan
07-09-2002, 12:12 PM
It does not happen all the time about it happens enough (say, 60%). It usually happened when I turned on the A/C during city driving. You can really hear that high pitch noise when those turbos kick in .... at least I think its' the turbos. Sometimes the turbos would slow down after some freeway driving. Other times it would not slow down at all. Despite the turbos are spinning very fast the car does not run any hotter. During those times the only way to slow down the turbos is to turn off the A/C. Any advise?
The turbos don't kick in when you turn on the A/C. The turbos kick in when you mash the gas pedal, and even there, then the A/C compressor turns off if you've been flooring it for more than about 5 seconds.
Singletrack
07-09-2002, 12:42 PM
at specific RPMs of the engine and in specific gears with specific applications of the throttle.
I doubt the sound you are hearing when you turn on the AC is the turbos, especially at idle or when stopped. The turbos do spin at idle, but I certainly can't hear them. Are you sure you aren't just hearing one of those high speed ball bearing fans that are responsible for the air distibution in the cabin?
-st
dcquan
07-09-2002, 01:03 PM
It could be the radiator fan. But I have never heard a fan sound like that before, a rather high pitch noise. The spin speed always drop a couple of seconds after I turned off the A/C. The noise definitely came from under the hood. The bottom lines is that no one had experienced a high pitch noise comming on after they turned the A/C.
Heavy G
07-09-2002, 01:40 PM
Yes, I have, but I do not have the 2.7T so no turbos. I have a 2002 3.0 A6. The high pitched noise is definitely there when you turn on the A/C. I got the car in February and when I first turned on the A/C in the spring, I was suprised to hear that not so pleasant whurr. I haven't had it checked out yet. Let me know if you find out anything...
timcar
07-09-2002, 01:46 PM
Don't know if what we hear is for the radiator, or just associated with the air conditioner, but it's always there when the air is active, and always absent when it's turned off.
CalmDriver
07-10-2002, 10:01 AM
I'm afraid you have the same problem that I and many others have - when the A/C is on, the fan sounds like a high-pitched jet engine. It is very loud and many others on this forum have mentioned it. If you search the A6 forum for "jet engine noise" you will find a bunch of messages. One person reported that the problem is a sensor, another reported a programming problem that runs the fan at too high a speed. The dealer can fix it.