need help with the vent

[slo95]

I have a 88 notchback that was once just a roller. The engine bay was stripped clean. What I need to know is what makes the vents change from defrost to dash to floor etc. It is on the defrost now and I need to get it to blow out through the dash. It's hot in Fl without an A/C. Someone told me that it changes by vacuum. The only line that I can find comes out of the passenger side firewall and currently goes to nothing. The only vacuum lines on the car right now is the line from the carb to the brake booster. Any help is appreciated.

[Viper_ed]

There is a single vacum line that comes out where the heater core comes thru the firewall that has to be hooked up to a vacum source.

[slo95]

thanks, I'll give it a shot.