A/C idle increase

[Lt.Del]

Ok, now that I have figured out one problem w/ my A/C, i want to turn to the idle.  On my 91 sub, shouldn't the idle increase when running A/C?  Because it doesn't.  What is supposed to make the idle increase, whatever it is, maybe mine is malfunctioning.   My sub idles very low all the time.  I just think the rpms should go up w/ ac on.

thanks

SgtDel

[VileZambonie]

The RPM shouldn't go up it should just compensate for the load when the compressor is energized to maintain the same idle speed. So you don't notice that annoying idle surge when the compressor clutch cycles. The PCM just moves the pintle on the IAC motor on the throttle body to compensate for the increased engine load. If you hook up a scan tool you can see AC request at the PCM when it's on and you can monitor your IAC stepper counts to verify the PCM is commanding the IAC to compensate for increased engine load.

Are you saying the idle speed drops and is not maintained when the compressor is energized?

[Lt.Del]

NO, I just thought I would notice an idle increase.  I guess i am from the old school.

There is a slight roaring from the compressor when at idle at a stoplight and such. I can tell it when the rpms go down when stopped. It doesnt effect the perfomance of the a/c, just irritating.

Thanks