I haven't figured out exactly what makes the difference for the auto climate control in my 08, but it will occasionally turn on the AC when I first set the system to auto (usually keep the system off) or when starting the car with it turned to auto. I've also noticed that it will turn off the AC light sometimes after running for awhile with it on.
Either way, everything seems to work fine so far as temperature and keeping my windows clear.
Either way, everything seems to work fine so far as temperature and keeping my windows clear.