Heating System

The heater air plenum chamber (18471) is located in the passenger compartment. It contains the:

• Mix door (for directing a mixture or total air to the floor and/or defroster/demister outlets)
• Temperature blend door
• Panel/defrost door
• Cam/crank that operates the temperature door
• Heater core (18476)
• Vacuum control motors (18A318) that operate the mix and panel/defrost doors.

The windshield defroster hose nozzle (18490) is formed into the instrument panel with outlets to the windshield and hoses that attach to an adapter located in the center of the instrument panel (04320) for demisting.

The A/C control (19980) is installed in an opening in the instrument panel. It contains three knobs (18519). One knob operates the four-position heater blower motor switch (18578) and one function selector switch that selects the function under which the system will perform (OFF, MAX A/C, NORM A/C, VENT, FLOOR, MIX or DEFROST) by controlling the vacuum control valve that controls the vacuum logic. The third knob regulates temperature by means of an A/C temperature cable (19988) that controls the position of the temperature blend air door.