Ok, so its friggen hot! Since i havent been driving much due to working 6 days a weeks and the 7th is for household duties (wink) i havent driven the bird in a cpl weeks> So I went out to recharge the ac today...no matter what setting i put the switch on, the air is blowing out of my defroster....all that wonderful cold air is blowing into the windshield and not my sweaty face.....any ideas?
92 Firebird 305

 

The defrost setting is the default it goes to if there is a vacuum leak. Carefully check the vac lines going to the back of the HVAC controller or underhood. Happy hunting

 

Check to see if you can hear a hissing sound when you switch the control from heater to air it could possibly the valve that switches it from max to cool heat and so on it has a rubber gasket that makes it leak they are bad for that.

 

I had this same problem in my 88 IROC. I tore the whole dash apart before I realized it was the vacuum control valve on the back of the A/C-heater controls. It is a round plastic piece with several vacuum lines connected to it. The shaft in the center had given out so the selector wouldn't work. I found a new one at NAPA.