When I am stopped with the A/C on it starts blowing out warm air and when I took it to a shop they said the high pressure is reaching 500lbs before the fans turn on. When I am driving it seems to work fine. What is causing this and how can I fix it?
Probably a defective pressure transducer. The pressure transducer reading needs to be compared to the gauge pressure reading, which needs to be hooked up to a computer diagnostic tool to get the transducer reading. So you need to take it somewhere that has proper diagnostic equipment.
Is your Bumper-to-Bumper Warranty still in effect? If so, the A/C repair will be covered by that warranty.