Function

Air distribution system

General




The air distribution system consists of:
- distribution housing (1):
- blower fan
- damper
- filter
- recirculation throttle.
- air ducts
- vents.
Three dampers control the outgoing air to:
- the defroster
- the dashboard vents
- the floor outlets.
Fresh air enters through the gap between the hood and the windshield.
After circulating, the air leaves the passenger compartment via the evacuation valves in the cargo compartment.

Distribution housing




1. Defroster damper
2. Ventilation damper
3. Floor damper
4. Temperature damper.
By changing the direction of the dampers in the distribution housing, air is directed from the fan through the various air ducts out to the passenger compartment.
The temperature is regulated by mixing hot and cold air. The temperature damper is regulated by an actuator motor in vehicles with manual climate control (MCC). Electronic climate control (ECC) has two actuator motors and a split temperature damper. This makes it possible to have different temperatures on the driver's side and the passenger side. The dampers are regulated proportionally to ensure that the passenger compartment achieves the selected temperature.

Damper and damper motors
Dampers controlled by several damper motor modules (DMM) are located in the distribution housing. For further information, see Design and Function, climate control module (CCM).
Electronic climate control (ECC) has five dampers and damper motors. Manual climate control (MCC) has four dampers and damper motors.

Recirculation damper
There are two ways for the ventilation system to draw in air:
- through fresh air from outside via the gap between the hood and the windshield
- recirculated air from the passenger compartment.
The air distribution system therefore has two air inlets. These are closed alternately by a flap (recirculation damper).
The recirculation damper is speed controlled, which means that the damper reduces the size of the hole to the air inlet the higher the speed. This is done to keep the airflow constant, irrespective of the speed of the vehicle.

Dashboard vents




There are four vents on the dashboard. Two are located in the middle at the front and one on either side.
The air flow can be regulated, fully closed or steered in the required direction using a damper. The damper is controlled with the thumb wheel located on the side of the vent. (See illustration).

Defroster vents
There are four defroster vents, two for the windshield and two for the front side windows. The two for the windshield are designed so that the majority of the air is directed up against the windshield. The remaining air trickles out at the bottom edge of the windshield to help keep the windshield wipers free of ice. The air ducts to the side window defrosters are a continuation of the windshield ducts.

Floor vents
There are four air vents in the floor. Two are located directly beneath the soundproofing panel, under the steering wheel on the driver's side and directly below the glove compartment on the passenger side. The other two are located one under each seat and face backwards.

Evacuation valves
In 4-door vehicles, the air vents are located at the edge between the parcel shelf and the rear windshield. The air goes from here through the cargo compartment and on out through the air vents behind the rear bumper. In 5-door vehicles, the air passes directly out through the air vents in the cargo compartment.
There are rubber flaps in the air vents. The flaps open when the air pressure is slightly higher in the passenger compartment that outside. When the air pressure is the same on the inside and the outside, the flaps close. This prevents water from penetrating.