it could be the heater is leaking!
I have exactly the same problem on my 2000 Still looking for the answer
heater core is shot and you have to get a new one
the middle vents only supply air from the ac unit using a separate in dash fan. the floor and defrost vents come only from the heater
The 1984 Buick uses vacuum lines to change air flow from defroster to ac vents. Check the entire vacuum system for leaks.
The little vents (or flaps) inside the heater system are stuck, broken, lost power (they're vacuum motors).
My ac blows only in the defroster and not any of the other vents i have 98 ford windstar 3.8 v6
It should blow through the floor vents. Modern vehicles generally use movable baffles in there HVAC systems, to direct air flow where the controls indicate. If the controls allow airflow to the floor, but nothing flows out, there is a malfunction between the control switch and the actuator that directs the flow.
This means that you have either an issue with a vacuum line or one of the a/c - heater doors behind the dash is not working correctly and you need to start off at the a/c - heater controller to check that all positions are working...........
I think your refering to the door in the heater housing that directs air to vents, floor or defroster vents, there is also a blend actuator that mixes heated or cooled air to give the correct temperature from the selector.
usually the air conditioner drain tube is plugged up, if water doesn.t run out freely when the air conditioner or defroster is on, chances are the evaporator core drain is blocked and the water in the box has begun to smell. The alternate possibility is that someone who doesn't like you has put fish guts in your heater intake.
That is actually how the vehicle was designed. If you look at the selector knob for the vents you'll notice that the arrows pointing down and for the windshield are white and the vents for the dash are blue. Basically, you can defrost and warm your feet and that's it