Vacuum Hoses
WARNING: This page is about a different car, the 1996 Ford Ranger and 1996 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
An A/C plenum vacuum harness, which is attached to manual A/C control, directs vacuum to the different airflow doors within the heater air plenum chamber. Blower Control & A/C On-Off Switch
The rotary blower control switch on control assembly controls blower motor speed (low, medium-low, medium-high and high). With function control knob in OFF position, blower motor will not operate.