I have a CLS6 and everytime I have the AC on, then press in the clutch while slowing down the RPMs seem to dip very low (about 4-500 and back to normal). It only does is when I run the AC and never has stalled. Could it possibly be the IACV I hear everyone talk about being dirty or faulty?

 

It could be slightly dirty. Does it do that when the AC is off?

 

The only time I've seen the problem is with the AC on. Possibly a bad compressor?

 

Doubt its the compressor.

If you turn the steering wheel at idle, does the idle drop too?

Its been awhile since I drove with the a/c on at idle, so it may be normal.

 

well when the a/c clutch is engaged its drawing more load so it should dip for a moment, but not sure if it should be at 4-500 rpm

 

My car does the same thing, so you're not alone. Doesnt bother me too much, the car is always a little funky when returning to idle anyway.

 

Thanks for the replys... I don't use the AC too much either, just started to get a lil hot in the northeast. Only problem is it gets on my nerves while driving in traffic, feeling like it wants to conk out every time I push the clutch in. Maybe ill start taking the scenic route home w the windows open.

 

i believe what compensates engine speed when a/c is turned on is activated by a vacuum hose... do you see any loose hose by throttle body? hear any hissing sound? does it idle a bit up and down if a/c not engaged?

 

Other than when the AC is on, it idles and drives absolutely perfect. The only thing I thought it MIGHT be is there is more drag on the motor with the AC, right? So, maybe before I push the clutch in it is used to the extra RPMs and killing that extra power may drag it down. I don't know maybe Im just making excuses for it now.

 

It could just be the parasitic drag on the motor. It could also be the pressure switch, but since the RPMs rebound to normal, I doubt it.

 

Mine has done this for a few years now, can't say it really bugs me cause it hasn't ever stalled out.