High Idle with A/C on

[dwithers]

The engine idles at about 400 to 500 rpm's higher with the A/C on than with it off. The car idles great with the A/C off. It idles high both in park and drive.

Any ideas?

The IAC is new.

 

[turbosam6]

vacuum leak, maybe at the heat/ a/c control box? Its supposed to idle up a little I think, but not 500 rpm.

 

[scottyb]

Not a guru, but some thoughts.
The computer controls the idle, so take a look at scan readings for IAC during this time. I'd think that it is maxing the IAC in attempt to control, which would support a vac leak theory. Or the chip itself is bad and is making no/bad IAC adjustments. I read once that the chip controls the "A/C request" and bumps the idle when the compressor kicks on. Perhaps it should lower the idle after initial "request" and yours does not.