Ok I have a '96 camaro lt1 and the for some reason when I turn on the air it only comes through the floor vents and the defrost no matter what setting I put it on. What the heck do I do to get this fixed, I have never even heard of such a thing happening.PLEASE HELP!!!!!!!!!

 

" Restore Airflow to the Dashboard Vents



This is a common fix for when the air no longer blows out the vents. When there is not enough vacuum to operate the actuators, they will only direct air to the floor and defrost ducts by default. Diagram of HVAC system.
An easy way to tell what part of the system may have trouble is to go to the vacuum check valve and test the lines back to the mode selector, intake manifold and to the vacuum tank. The check valve often cracks and is the source of a leak, so be sure to inspect and/or test it.

A hand held vacuum pump (like a Mityvac), makes testing pretty easy (your lungs can be used as an alternate vacuum source ;-) ). At the check valve, remove the hoses one at a time and apply vacuum to each and see if it holds. The line to the intake manifold will have to be removed at the manifold and plugged back toward the check valve for you to test the line for leaks. If you find a leak on a particular hose, you will have to trace out the cause on that section. " - Entirely jacked from http://shbox.com/1/4th_gen_tech2.html#pass_key

- Z28WAnnaB

 

I'd start by locating this valve, which is passenger side near the A/C lines. Is it cracked? If so replace.

http://shbox.com/1/vac_check_valve.jpg