no ac through the dash

My AC, heater and vent all work. The AC is cold, but it will only blow through the floor vent and the defroster. I have checked all the vacuum lines and everything's looks to be connected. Under the hood there is one vacuum line that is tied off. I am sure this is my problem, but I can figure out where to hook it up to. Any ideas?

Thanks,

Jerry

did u check the plastic hoses that go from the damper area behind the dash...they may not be connected and you migh just be blowing air behind your dash.