Saturn - Vuehybrid :: 2007 - AC Malfunction / Stopped Working

11 months and 3 weeks ago a mechanic I trust replaced my a/c. Two weeks later I rear-ended another car.

There was minor cosmetic damage but it ran as before. A week after that began the record setting Texas summer heat wave and my car got so hot the mirror gauge registered 125 in a fast food line. This is the only time it got that hot. Once we got moving everything seemed fine.

A couple of days later the a/c ran for about 10 minutes then stopped. Slowly the time the unit cooled decreased until it stopped working. I took the car back to the mechanic. He stated the pressure measured up to 100 psi and the temperature was above the rating for the a/c system.

He fixed a short in the radiator/engine fan, the temperature problem never returned and the pressures were high but my a/c worked.

At first the a/c seemed to work fine but then it began to work only sometimes. When it did work it would sometimes work in "hybrid" mode which you Saturn owners recognize as cooling at the reduced level that saves gas in stop and go traffic -- or not at all as we say in TX.

I took it back. The mechanic now explained the I'd voided the warranty because the short in the radiator fan allowed the car and a/c system to get too hot. The high heat had burned some sort of internal valve in the compressor.

The valve is unreliable. The performance of the a/c is mainly temperature dependent. The hotter the day the less likely the a/c will produce enough of a pressure difference to open this valve. Warm days the system will probably cool. Hot days it will probably not.

Being a CarTalk listener and an former nerd I thought of and tried a way to magnify the pressure difference using rpm. It works but the hotter the day the higher and longer I have to rev the engine. Now I'm burning oil for the fist time ever. Did I cripple my air conditioner or does my trusted mechanic learn a little to little when he learned to repair my hybrid a/c system?