I have the same problem, 90 degrees (hot for MI) here with car sitting in the sun, passenger side cold, driver side hot. Later in the day sitting in the shade the passenger side was cold and the far left drivers side vent was cold and the center driver side vent was hot. That night the AC worked fine. This has only happened twice, once last year and then couple of days ago. I'm thinking it's electrical but I have no idea what. Maybe if you had a way to cool down the car, to sed if the AC comes back. Don't think it's mechanical because all the controls work as they should. Any ideas would be greatly appreciated.