Vehicle - 89 Firebird Formula 350 WS6 (stock)

Heater comes on and work, same with AC. The problem is no matter what I switch the slider to, it comes out through the top vents on the dash.The windshield defroster ones. Why would it do this? Cannot get it to blow air through other vents.

 

Have you done a search?

The dash vents are vacuum operated. When the vacuum system fails, it defaults to defrost. It could be the line under the hood to the engine, or the valves in the HVAC control unit, or any of the plumbing in between.

 

Anyway I can get some pics or diagrams of where these things are exactly. I would rather start with under the hood. where exactly is it located? Thanks.

 

did you fix the problem? i have the same problem and i think it has to do with these two vacuum hoses on the passenger side firewall? but have no idea on where it goes. help please!!!!!!!