Alright guys, I've taken the blower motor fuse out, it's not blowing anything through the defroster & no leaks so it's not heater core, but the thing just blows hot air though my defrost vents, also lowers get nothing, but hot air just steadily blows outa the top side, this has to be due to a bad vacume somewhere, but I don't know where to look...

Any ideas would be helpful, this is on an 82GT, btw

 

On the later cars there is a vacuum tree behind the HVAC controls where hoses often get unplugged, that could be your problem.

 

http://vb.foureyedpride.com/showthread.php?t=46533