Hi, My uncle has a 2002 Firebird in Sunset Orange...last night he had a problem and I checked it out...when selected to MAX, A/C, top/bottom a/c, and windshield defrost...the a/c compressor runs and the tube going to the evaporator is chilled cold and dripping condenstation.

BUT...there's only heat coming out of the vents in the car. Even turning the temp control knob from full cold to full hot didn't do a thing.

I know it's stuck in the heat mode because as the engine warmed up, the air coming in the car got hotter.

It appears like there's a valve in the air disturbition system that's stuck closed or stuck in heat mode passing all the air thru the heater core and bypassing the evaporator...

the vaccum line from the temp control to the valve control has a leak or break?

does it default to heat mode when there's a break in the line?

I have read a long time ago on ls1.com before the site got overhauled that someone mentioned the flapper for the cabin air intake was stuck closed by mud and all it took was a small push to get it to open and free it.

Does anyone know where the intake for the cabin air is located? I'm thinking it's under the car behind the pass. front wheel but where exactly?

Or any other sugguestions on where to look for like access to the valve that control the air?

Thanks in advance...