[FlyingDutchman]

Today I decided to trouble shoot my air conditioning system in my Camaro. It hasn't blown cold air since I bought it late 2008. Without it I sweat in the summer and can't see to save my life in the colder months. I took it to a mechanic thinking it needed more Freon, but it wouldn't take any. Kinda pushed it to the side and forgot about it.

Lately, its been too hot to live. So I did some research and noticed the compressor did not turn on. Switching relays didn't make a difference. So I jumped it and found it kicked on which was indicative of low freon. Bought 2lbs of R134a and evacuated the system (some residual pressure). The system held 28-29psi vacuum so I am assuming no leaks.

After emptying a can, I started the car with A/C on MAX. Compressor kicked on like it should and I added the second can. Car now blows cold (around 60*F) and I was a happy guy until I drove down the street.

I left the car idling for a good 10 mins before driving (during that time the A/C was still nice and cool). Less than a mile away the air became really hot like it was outside.. because it was. Got all the way home and sat there playing with the dials but the compressor would not cycle back on for anything. Turned the car off, waited a minute, restarted, and the compressor ran fine and I had cold air.. but as soon as I drove around it would kick off and not come back on unless I restarted the car.

Hooked up a set of manifold gauges and found 250psig H / 43psig L which dropped to about 225psig H / 36psig L (which are good values for 90-100*F greater than 40% humidity based on A/C performance chart). Played with the throttle and engine rpm didn't make a difference either, compressor kept running. This was a while later so I did not lose pressure from when I filled it to when I checked it later.

I decided that maybe the really hot air was too much, so I waited until dark. Same problem though, compressor on at idle but after driving turns off and does not come back on without restarting. Really not sure what to do, looked all over but could not find an other problems.

I don't suspect any vacuum issues (recently resealed the intake) due to the vents all working properly. Im guessing electrical, like maybe a pressure switch? Obviously the car knows there's enough Freon now to start the compressor. High pressure switch next to the passenger strut on the high side line? Not looking to shotgun parts at it or disassemble something when the heart of the system works fine.

Any tips?