In most vehicles I have owned, there is a component that increases the idle setting with the AC is turned on. On my 92 Geo Metro is also increases the idle when the voltage drops a certain amount. I have noticed that my DeLorean does not do this so I have to do it manually. If I am at idle with the AC on the voltage guage drops well below 12 and if the lights are on it's even worse.
So.. is there supposed to be an idle increase? If so and since I'm not seeing that, where should I look first to fix it?