It turned out to be a blend door actuator which I bought at the dealer for about $40. Easy fix once I figured out what was wrong. There are several actuators on the left of the dash, one controls the flow of air between the various vents defrost, floor, panel, etc and the other controls the exchange between heat and cold. Once you figure out which one is broken, get on your knees and remove the metal kick panel under the steering wheel. Then get a flashlight and look past the gas petal under the dash and you will see one. The first on my 2006 magnum control air flow. I had to remove it to get at the other one right behind it. Only took 45 minutes at a total cost of $40. The dealer wanted $500 and a local garage $350.