I have a 2000 Audi A6, Quattro 2.8L. For the past month the AC fan runs on high as soon as the car starts. The only exception is in the morning when the engine is cold; then it takes a minute for the fan to switch to high. It sounds like an airplane. Any idea what the problem may be? Is there a temperature sensor or sending unit that could be malfunctioning? Thanks!

 

No malfunction, just an interesting phenomenon known as global warming. It's been really hot lately!

When you turn the AC on to "Auto" it takes a moment to let the car warm up before kicking on the AC compressor. While this is going on, the HVAC fan (determines how much air comes out the vents) is off or on very low. As soon as the AC is able to fully spin up, the HVAC will then kick on like all hell is braking loose in an attempt to cool the car down. You can manually crank the fan down a bit if this is too loud for you to tolerate (I either do this or crank my tunes to compensate). As soon as the car gets cooled off to the temp you've selected, the fan will throttle down. If this has not been happening very quickly lately, I have a hunch nothing is wrong -- it's just been really hot!

Sound right?

 

Thanks for the reply but I meant the AC cooling fan that sits beside the engine cooling fan, not the interior AC blower/fan. Sorry for the confusion. The AC fan sits to the right of the engine cooling fan and runs on high all the time. Its very loud and sounds like an airplane or siren. If I shut the AC down, the fan shuts down after a few seconds and the noise stops.

 

Ah. Sorry -- nothing to offer on this one. Good luck.