Air Distribution System

Air distribution system

General




The air distribution system distributes the air to the passenger compartment. It is used jointly by the heating system and the cooling system in the climate control system. The blower fan draws air into the system. Fresh air enters through the fresh air intake in the distribution housing under the plenum chamber.
The air passes through the filter and the evaporator, past the temperature damper and possibly though the heat exchanger, before being released into the passenger compartment through the vents.
The temperature of the air from all the air vents can be controlled separately for the right or left hand sides.
After circulating, the air disappears out of the passenger compartment though air vents at the rear of the vehicle.

Recirculation
The recirculation damper regulates the amount of incoming fresh air. The recirculation function makes it possible to prevent outside air from entering the passenger compartment, for example when the ambient air is contaminated with exhaust fumes, smoke, etc. This function can also be used for rapid heating or cooling of the passenger compartment.
If the recirculation function is used for an extended period, the air humidity in the passenger compartment increases. This is because of the humidity of the expelled breath of the passengers. This can result in mist on the windows. The recirculation function has a timer function to eliminate the risk of misting.
When the controls are in the Maximum cooling position all the air is taken from the passenger compartment. This produces more rapid cooling of the passenger compartment air.
In vehicles with an air quality system (AQS), the transition to recirculation takes place automatically if the level of contaminants in the outside air increases, when the system is in the AUTO mode.

Defroster vents
Mist forms easily on the windows in cold, damp weather. The defroster vents release air towards the front and side windows. The air flow removes the mist that forms. As the air is dry, the airflow also prevents moist air from the passenger compartment reaching the glass, so countering misting. The air conditioning contributes significantly to these functions by dehumidifying the air at temperatures above 0 °C.
The defroster function, for the electronic climate control system (ECC), automatically sets the climate control system for the best defrosting of windshields.

Evacuation valves




The evacuation valves are used to even out the pressure in the passenger compartment.
The rubber dampers in the evacuation valves open when the air pressure is slightly higher in the passenger compartment than outside. When the air pressure is the same on the inside and the outside, the rubber dampers close. This prevents water and air (odors, dust and exhausts fumes) from penetrating the passenger compartment.

Note! The evacuation valves must not be blocked, this will impair the function of the climate control system.