My daughter's 2010 C30 cools the car just fine, but only for about ten minutes and then it blows warm air. She turns it off at that point and waits a few minutes before turning it back on. Once on, it works fine for another ten minutes. (It has nothing to do with acceleration.) Guys at Meinecke where she stopped in, told her it needed recharging. That didn't help at all - waste of money. They told her it must be the compressor for $2k. After reading other similar problems, I wonder if it has to do with a vacuum or sensor or relay. Had my local mechanic look at it and he replaced a relay but said it didn't help, so he thinks compressor. Any other ideas? How do you test for a vacuum leak? Thanks for any and all advice!