System Air Flow

SYSTEM AIRFLOW DESCRIPTION
The Airflow Diagrams illustrate the path airflow takes in response to each functional setting of the control knob.






OFF
In the OFF position, all doors are in the vacuum-applied position with the exception of the PANEL/DEFROST door.






MAX A/C
In the MAX A/C position, all doors are in the vacuum position with the exception of the HEAT/DEFROST door. Outside air is shut off and the passenger compartment air is recirculated to maximize cooling.






NORM A/C
In the NORM A/C position, outside air is allowed to enter the passenger compartment. The air passes through the A/C evaporator core and is cooled before reaching the passenger compartment.






HEAT
In the HEAT position, no vacuum is applied to the vacuum control motor and the outside/recirc. door is open to the outside. Air is discharged through the heater outlet floor duct with a small amount going to the windshield defroster hose nozzle.






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






MIX
In the MIX position, outside air is discharged through the windshield defroster hose nozzle and the heater outlet floor duct.






DEFROST
In the DEFROST position, outside air is discharged through the windshield defroster hose nozzle with a small amount going to the heater outlet floor duct.

Some generalizations which may not be apparent in the data provided in the airflow diagrams include:
^ The temperature blend door, when fully open, directs all incoming air through the heater core. Conversely when the door is fully closed, all incoming air bypasses the heater core. Between the two extremes of fully open and fully closed, the extent to which the door is open determines how much heated air blends with whatever outside or recirculating air enters through the outside/recirculating air door, crosses the blower motor, and then passes through an activated or dormant A/C evaporator core en route to the heater core.
^ When the system is set for MAX A/C, the outside/recirculating air door is set to seal off outside air and allows recirculated air from the passenger compartment through the system. This exposes the passenger compartment to the normal operating noise from the blower motor. This increase in noise level might be confused with an increase in speed when, in fact, speed responds only to the heater blower motor switch in the A/C control.
^ Operation can be stopped only when the function knob is placed in the OFF position.