I have a 2009 Chevy Traverse and lately we will be driving and the circulation button on the ac shuts off by itself. it happens often and then last week we were driving and noticed the circulation button shut off and then the whole car shut down and then came right back on. We took it to our local chevy dealer and they said that they couldnt find anything wrong and we asked about the ac and he said that was normal and that all cars circulation buttons shut off to let the old air out and then comes back on. i have never heard that and never noticed it before. Has anyone else had this happen to them?