ok i have a 88 pontiac firebird and no air comes out of the vents only defrosts?

 

You have a vacuum leak from your diverter controls. When that hapened to me, I found the leak right next to the firewall in the engine bay.

 

you know what color the line is and where the line goes to

 

The lines are all black.... so.. uhh.. good luck

Those vacuum lines are hard to track down.

 

is the line in the main wire harness

 

Check all vacuum tubes and hoses under the hood before tearing down the controls.
My first van had that trouble for a while,it was simply a little white tube under the windscreen that had been pulled out of where it was supposed to go.

 

 

you are not alone my friend, i have the same problem, took apart the dash looking for something, didn't know what, but now i know... and knowing is half the battle. now i have to try and recharge my a/c and fix the vacumn leak.

GREAT!