Mine too was intermittent. Some days it works, some days it only blows cold. I had a ranger visit and it happened to be working when he was there. He said there were no error messages logged, so he couldn't diagnose the problem. The next day, I called the service number while I was inside the car and it was blowing cold air, and they discovered some error codes from a something-or-other-module-with-3-words-in-the-name. Apparently these codes aren't logged anywhere, but they said to bring it in. He implied that parts would be ordered from California. So my car is currently in Rockville being examined. Free loaner car, of course (no, not a Roadster :-/ Just some car from the Enterprise around the corner).