engine not raising idle when turning aircon on

[ernbuild]

When I turn on the aircon on my91 zr1 the engine idle is not increasing and if I roll to a stop at lights or such engine will stall. Is there some sort of pressure switch on the coolant line that is supposed to do this?
Also can you buy the clutch assembly only for the aircon unit as mine is making a heap of noise even though the aircon is working.

[Hib Halverson]

Idle speed is controlled by the IAC motor. When the A/C is turned on, the engine computer increases IAC counts.

Now, if your engine is not idling properly, then you need to approach the problem as an unstable idle or stalling problem, not an A/C problem.

Consult the section in your Factory Service Manual which covers troubleshooting idle stability problems.

[ernbuild]

Thanks Hib, I have the manuals so will give it a go.

[GRAND SPORT #12]

Hib i dont know if this is correct and applies to chevy, but on toyota if the idle starts droping real low you can dissconect the battery and clean buildup on the throttle body to restore proper idle level. I have heard that on some cars you can not clean the throttle body for risk of removing protective coating in the throllte body opening at the butterfly. So i dont know if this would be good advise to start out with