Has anyone had intermittant ac problems? On my initial test drive of the v8 sedan, the ac would not work - drove with windows down for about 5 minutes when it decided to work, enjoyed the quiet ride with windows up. Second test drive, without wife, was fine. Dealer closing/pickup and the ac would not work!! Still in shop...any suggestions? Is this common? Read about the hot air out of rear vents, but nothing like this.