i've been having a similar issue on my girlfriend's 2010 SS. It was fine at first, then all of the sudden would blow hot air. had it in my garage with the hood open, started the car and turned the a/c on. At first the compressor was running then all of the sudden it stopped and started blowing cold air. During our heat wave a couple weeks ago, it just wouldn't blow cold AT ALL. Now that the ambient air temps went down, the a/c is working again. Did anyone experience this at all?
Oh, we also took it to the dealer we purchased the car from (great people in the shop) and of course, the air worked flawlessly once it was in their hands. They did however update the BCM. The a/c worked for about a week straight after this, now we're experiencing the problem again.