Actually, the engineers have found a need to computerize everything imaginable on today's vehicles, (it's why I still drive an '88 Grand Caravan). Instead of simple, reliable levers and cables, a computer module runs the door actuators in the heater box.
Is there a possibility the battery was recently disconnected or run dead? On the '96s and '97s, the heater computer had to be recalibrated which was often a real frustrating job even for the professionals. I think they improved that silly quirk by '98 or '99, but there still might be a calibration issue.
Another somewhat common problem is intermittent connections on the module connector pins. In the past, GM was famous for having all kinds of intermittent computer problems while Chrysler had very little. Lately, Chrysler has been succumbing to more and more computer trouble so a defective computer is a likely suspect. The temperature door and the vent / floor / defrost doors are totally independent of each other, so the fact you're getting hot air from the heater, and that it is switching to defrost suggests both actuators are working. Sorry to say, but the computer looks like a likely culprit, but first I would ask the dealer if there is a recalibration procedure that might help.
Friday, December 11th, 2009 AT 12:10 AM