So im finally get my car back together, and putting in the heater box (86 tpi) and everything (yes just in time for summer) but anyways, the air wont come out of the vents, im pretty sure this is a vacuum problem beacause the little doors right after the heater core that let the air through the vents are not opening when i move the control

Does anyone know where the heater controls get their vacuum from and where whatever that is would be located, thanks.