The vacuum circuit is controlled by this vacuum diverter, a routing device,
or switch, connected to the mode selector.
The diverter has seven ports, which are either connected to or isolated from the vacuum
supply, port F, by a moveable template.
As successive mode selections are made, the template rotates and applies vacuum to,
or vents the lines to the flap actuators.
As you see here the face level flap actuator 1, is connected to ports A and B,
one to each vacuum chamber. The distribution flap actuator 2, is connected to part G,
and the fresh air/ recirculation flap actuator 3, to port E.
The line from port D is joined to port C through vacuum switch 1 the switch is operated
by the blower speed lever. It ensures that the fresh air vent is closed by applying
vacuum to the fresh air/recirculation flap actuator whenever the air conditioning is
A second vacuum switch is connected to the temperature selection lever.
In the full cold position the switch 2, applies vacuum to the water valve and stops
engine coolant flowing through the heater.