Could be that there's a problem with the idle speed control valve/motor-not raising the idle speed to compensate for the AC load. When the computer sense an electrical load it tells the idle air control to increase idle speed so that the alternator turn faster and produce more output voltage to maintain the electrical load.
May, 22, 2008 AT 2:01 PM
The engine idles very smoothly and does not seem to be any different than when the AC is off. The car never stalls or anything like that.
Could it still be the idle speed control valve?
The battery and alternator have been load tested and test good.
I can turn on all other accessories together and the battery gauge hardly moves.
Only the Air Conditioner drops the battery gauge.
Thanks for replying,
May, 22, 2008 AT 5:52 PM
As I mentioned earlier could be the ISC motor not functioning properly. AC dropping voltage could be be normal if not excessive.