ZsTransAm

Sorry about the title, the computer somehow submitted the post before I finished typing.

My heater was only working on defrost so I took apart the heater controls to try to fix the problem these cars have with the selector where all the vacuum hoses plug in. I soaked the rubber disk in brake fluid then replaced the plastic clip that holds the two pieces together with a nut and bolt like I've read you're supposed to do but it still doesn't work. In fact it works exactly the same as when nothing is plugged into the hoses at all. I feel no vacuum coming from any of the hoses. Where do these hoses get their vacuum from? Is there another weak spot that I should check?

sonjaab

The hose gets vaccuum from a line thats plugged into the intake manifold
behind the carb.
The hose runs to the firewall and then splits and runs off a T connector to both
the cruise control vac. orb and then thru the firewall to the heater control.

Start at the manifold connection to check for vac/bad hose and work toward
the firewall.............

I have the same issue!
Pretty sure its a vac. line leak/plug/pinch behind the dash.
Having defrost only is the default mode when there is a vac. problem.