Hi All,

I recently got my throttle body cleaned, and my air conditioning recharged, and now, when I switch on the air conditioning, the idle revs start to fluctuate massively for the full duration of the air conditioning being on.

There is also a strange noise coming from the bonnet when the AC is on. When I opened the bonnet, it looked like some kind of belt pulley not quite functioning properly, and the pulley was only turning sporadically. Is there a belt used to drive AC?

The car runs fine when the AC is not on, its only when the AC is on that the noise occurs, and the revs fluctuate.

Does anyone have any experience of such faults and what could be the root cause?

Thanks for your help

Sumz

 

From experience (not with Audi's but in general) when you switch the AC on it will drop the revs a little because the engine now has to drive the AC unit.
Sounds like the pulley you say is turning sporadically is for the AC and if its turning on and off it could be making the revs jump about.
With the engine off check if the pulley is loose and that the belt is tight. Sorry cant be much more help.