My A/C just began acting up. It blows cold when the car starts, then, after a few minutes, it blows warm until the car has been parked for a while. The Haynes manual contains no A/C information at all. (It just says "take it to the dealer". If I wanted to take the car to someone else to be fixed, I wouldn't be buying manuals.)

Is it safe to assume that a system that cools fine one day and then only cools fine for the first few minutes is not low on refrigerant? There have been some previous posts that said that A/C only on startup is a sign of a seizing compressor. Why would that make the A/C cut out? (In my case, the A/C clutch is disengaged.) Is there a sensor on the compressor that cuts out the clutch when the compressor generates excess heat?

Can anyone describe the power circuit to the A/C clutch, so that I can verify that all relays, sensors and connections are functioning properly?