The defrost vents at the bottom of the front windshield has no air coming out at all. The motor is running and blowing air but not to the defrost vents. What could be my problem. AC works, heater works just seems to be disconnected or pluged up.

The Vent Selector runs on Engine Vacuum

So behind the Selector panel will be 5 vacuum hoses, one from engine bay and the others run to the 4 "Vacuum Motors" that open and close doors that direct the air flow, well one is not for a door but not the issue.

Picture here of the lay out: http://www.explorerforum.com/forums/...iag-gif.41768/

Your selector is stuck, it is not redirecting vacuum to the correct places, or one of the doors/motors is stuck, the Panel/Defrost door.

Turn on key but leave engine off
Turn blower fan to high and feel Defrost vent, Defrost is the Default vent, no vacuum = defrost.
If air is only coming out of panel vents then the door is stuck, or vacuum motor is
If Defrost works with engine off then Selector switch is most likely the problem