Several times in the last couple of really hot weeks, my A/C has started blowing hot air after running correctly for a while. It will last for 5 or 10 minutes and then start blowing cool air again. When it does this, I cannot switch between the fresh air/recycled (cabin) air either, and I am reasonably sure that the compressor is not running. I'm still under warranty but my dealers favorite expression is "cannot replicate" so I would like to go in with something to tell them to look for. Any ideas?