Heater System Schematic and Selector Test

OFF

In the OFF position, vacuum is applied to the outside / recirc. door. In this position, outside airflow is shut off.

PANEL

Ventilation is delivered through the instrument panel registers when the function control knob in the control assembly is set in the PANEL position. In the PANEL position, no vacuum is applied to the door motor and the outside/recirc. door is open to the outside. The air coming in through the cowl is discharged through the panel registers.

PNL/FLR

In the PNL/FLR position, no vacuum is applied to the door motor and the outside/recirc. door is open to the outside. Air is discharged through the floor outlets and the instrument panel registers.

FLOOR

In the FLOOR position, no vacuum is applied to the door motor and the outside / recirc. door is open to the outside. Air is discharged through the floor outlets only.

FLR/DEF

In the FLR/DEF position, outside air is discharged through the defroster nozzles and the floor outlets.

DEFROST

In the DEFROST position, outside air is discharged through the defrosters only.

Vacuum System

The outside/recirc. air inlet door is vacuum-operated. The vacuum system schematic diagram illustrates, in schematic form, how system components are involved.

The source of power for the vacuum control motor which controls movement of the outside/recirc. air intake door is the engine intake manifold. This door has two operating positions, either of which is determined by the setting of the function selector lever in the heater control.

When the vehicle is equipped with heater only and the function selector lever is in its OFF position, vacuum will be applied and the outside / recirc. door will move to shut off airflow from the outside. In all other positions of the selector lever (PANEL, PNL / FLR, FLOOR, FLR / DEF, or DEFROST) no vacuum is applied. Since the door is open to admit the input of outside air, it is closed to the admission of air from inside the vehicle.

Door position can be checked by lowering the glove compartment door on its hinges so that the recirculating air inlet, located in the case, below the compartment will be exposed.