My temperature selector switch was not working. When I turned it to cold I got hot air and vice versa. Ran a diagnostic check of the blower motor resistor (which is bolted to the blower motor below the glove box) with a multi-meter and it was bad. Replaced the part and everything works fine.

 

Great piece of information. Right now someone is beating their brains out trying to figure this out. Now they know where to look.