System Airflow

SYSTEM AIRFLOW DESCRIPTION
The illustrations contain system vacuum schematics and vacuum motor charts which show vacuum routings and airflow when the controls are set at their various positions. Vacuum control motor charts illustrate vacuum line routings and air distribution during the various system operating conditions.

OFF
When the function selector knob is in the OFF position:
- the heater and A/C air inlet duct door is at full vacuum. As a result, outside air is closed off and recirc air is admitted to the system.
- the heater air damper door is at no vacuum and the windshield defroster door is at full vacuum, closing off the passages to the windshield defroster nozzle.
- the A/C air temperature control door position may be anywhere within its range of adjustment from FULL HEAT to FULL COOL.
- the blower motor is off.

PANEL
When the function selector knob is in the PANEL position:
- the heater and A/C air inlet duct door, with no vacuum being applied, will block recirc. air and admit outside air. From there, airflow is directed through the system to the instrument panel A/C registers.
- the heater air damper door is at full vacuum to block airflow to the heater outlet floor duct.
- the windshield defroster door is at full vacuum, closing off airflow to the windshield defroster nozzle.
- the temperature setting can be changed manually.
- the blower motor is on.

PANEL/FLOOR
When the function selector knob is in the PNL/FLR position:
- the heater and A/C air inlet duct door is in the no vacuum position, blocking recirculating air and admitting outside air.
- the heater air damper door is in the partial vacuum position, allowing airflow to both the heater outlet floor duct and A/C register.
- the windshield defroster door is at full vacuum, closing off airflow to the windshield defroster nozzle.
- the temperature setting can be changed manually.
- the blower motor is on.

FLOOR
When the function selector knob is in the FLOOR position:
- the heater and A/C air inlet duct door is in the no vacuum position to block recirc air and admit outside air.
- the heater air damper door is in the no vacuum position closing off airflow to the A/C registers.
- the A/C air temperature control door can be positioned to mix air flowing through the heater core and air from outside to achieve the desired temperature level.
- the windshield defroster door is in the full vacuum position to block air circulation to the panel windshield defroster nozzle.
- the blower motor is on.

FLOOR/DEFROST
When the function selector knob is in the FLR/DEF position:
- the heater and A/C air inlet duct door and the heater air damper door are in the no vacuum position.
- the windshield defroster door is in the partial vacuum position allowing airflow to both heater outlet floor duct and windshield defroster nozzle.
- the blower motor is on.

DEFROST
When the function selector knob is in the DEFROST position:
- the heater and A/C air inlet duct door is in the no vacuum position to admit outside air.
- both the heater air damper door and the windshield defroster doors are in the no vacuum position so that most of the incoming air is directed to the windshield defroster nozzles. There is also airflow to the window defogger nozzle.
- the temperature control knob setting will determine the amount of heat being introduced into the airflow.
- the blower motor is on.