Every time I turn my A/C on full blast my car shakes violently and makes knocking noises during idle.

With the A/C on full blast my 95 idles somewhere around 500 RPM's.
But, if I turn the A/C off or even lower the power of the A/C the RPM's go back to about 700 and the car runs fine.

I've tried adjusting the idle, with the A/C on. But that was a temporary fix. The computer saw to that.

So where do I go from here? Any ideas as to what the problem is?


It's more of nuisance than anything.

 

There is a Idle Up Control Valve that may be malfunctioning. It only kicks on when the AC compressor is activated. I would check that out next.