My A/C blows cold at start up and works well for ~20-30 minutes. I added freon and the gauges read 25 and 190. (The pressure actually came down after adding the freon; pre-adding the freon, the pressures were ~40 and 250). Once the car heats up, the A/C quits. If I turn it off for a few minutes it will come back on for a while.The compressor seems to be cycling correctly in the garage at idle, but to give the devil his due, I've not checked it when it has stopped functioning.