When I'm in park w/ AC on, it does jump to about 900 rpm. But in gear it's at 650rpm. I thought this was normal?? Can anyone else confirm?Why are you idling so low with the AC on @ 650? My rig idles around 800-1000 with AC on. Lower idle, means lower fan speed and less air being pulled across the radiator for cooling. I'd check on your IAC valve to get your idle to bump up some and beyond that you may look into an aux fan to boost your idle cooling.
AC on, in Drive: 650 RPM
AC off in Drive: 650 RPM
AC off in park: 650 rpm
AC on in park: 900 RPM
I have not looked at my IAC, will check on it today.