F 150 Super Crew 4WD V8-4.6L SOHC VIN 6 (2003)
Cabin Air Filter: Description and Operation
NOTE: A cabin air filter is available as a dealer-installed accessory for the air distribution system of this vehicle. Instructions for installing and
servicing the cabin air filter are included with the filter when purchased.
Air Distribution and Filtering
There are two sources of air available to the air distribution system:
-
outside air
-
recirculated air
Recirculated air is only used during MAX A/C (if equipped) and OFF modes.
The incoming stream of outside air is passed through the pollen filter, if equipped, and is cleaned of pollen and dint particles The pollen filter becomes
restricted with foreign material and contaminant and will restrict the outside airflow into the plenum assembly. A new pollen filter must be installed to
allow for free airflow.
Air distribution within the vehicle is determined by the function selector switch position. Airflow control doors are used to direct airflow within the air
plenum chamber. Vacuum control motors (18A318) are used to position these airflow control doors.
The air distribution system is designed to provide airflow from the defrost nozzle when no vacuum is applied to any of the vacuum control motors.
This is done to prevent a situation where defrost cannot be obtained due to a system vacuum leak.
Air enters the passenger compartment from the:
-
instrument panel A/C register (19893).
-
heater outlet floor duct (18C433).
-
windshield defroster hose nozzle (18490).
-
side window demisters.
Passenger compartment air is exhausted from the vehicle through open windows or body air vents.
