My uncle just bought a '96 Park Ave. and the air conditioner blows out of the defroster rather than the dashboard vents. Any ideas on how I can fix that for him?
There’s probably a vacuum line under the dash that’s worked loose. When you switch vent positions, it uses a vacuum to move the baffle and redirect the air. When the line works loose, suddenly there’s no vacuum anymore. Some cars make it a very easy fix - you pop a panel off on top of the dash and hook up whatever’s come unhooked. Others require a lot more digging to get at the lines.
It could also be the baffle itself - it can get corrosion or gunk in its guide tracks and stop before it’s supposed to. Sometimes you can see this by looking behind the glove box into the blower motor vent - you can see the door moving around, and whether or not it’s traveling fully. Not sure if you’ll be able to see that on the Buick, though.