Heater Switch

I need to know what the location is of the main tubing for the heater switch. Where does the switch get the suction from to run the other trap doors and vents. There are several tubes on the switch, but it appears that one is for the control and the others are for the various trap doors. Where is the air suppy for the switch Located??? Need help ASAP getting CHILLY here.

The switches are controlled by engine vacuum. Should be a hose running from engine area, just not sure where. If it is not controlling anything you probably have a bad vacuum leak in engine somewhere.