Ventilation system, function

The ventilation system ensures aeration of the vehicle interior (air circulation) and also ensures the following:

 the windshield and windows are kept defogged

 there is a good oxygen supply to occupants

 constant and pleasant temperatures are quickly achieved in the vehicle interior

Aeration can occur using one of the following two modes:

 Fresh air mode

 Recirculated air mode

Selection is made using the air recirculation mode and air distribution rotary switch. The rate of circulation and the distribution of fresh or recirculated air are controlled with the blower knurled wheel switch (A81s2) and the air recirculation mode and air distribution rotary switch which are integrated in the climate control control and operating unit (A81) (heater operating unit). To control of the rate of circulation, the output of the front blower motor (M4) is regulated by the blower knurled wheel switch.

To control of the rate of circulation, the blower knurled wheel switch can be used to set the output of the front blower motor using the blower settings 1-3 series resistor (R10) in the following 5 stages:

 Stage 0 (blower "OFF")

 Stage 1

 Stage 2

 Stage 3

 Stage 4 (max. blower output)

Distribution of the drawn in fresh or recirculated air can be controlled by means of the air distribution flaps via the air recirculation mode and air distribution rotary switch. The distribution of the suctioned fresh or recirculated air is possible in the following positions:

 Dash and footwell vents (3 o'clock position)

 Footwell vents (6 o'clock position)

 All vents closed (9 o'clock position)

 Dash and defroster vents (12 o'clock position)

 Intermediate positions are also possible in addition to the listed ones, e.g. when the air recirculation mode and air distribution rotary switch is in between the dash and defroster vents (12 o'clock position) and the dash vents and footwell vents position (3 o'clock position).

The drawn in fresh or recirculated air in the vehicle interior is then distributed depending on the position of the air recirculation mode and air distribution rotary switch using the following air outlets:

 Left footwell air outlet

 Defroster outlet for left side window

 Adjustable left side air outlet

 Adjustable left center nozzle

 Air vents for left head area and rear compartment

 Air vents for right head area and rear compartment

 Adjustable right center nozzle

 Adjustable right side air outlet

 Defroster outlet for right side window

 Right footwell air outlet

 Discharge of fresh or recirculated air is also still dependent on the position of the following adjustment wheels:

 Adjustment wheel for left side air outlet

 Adjustment wheel for left center nozzle

 Adjustment wheel for air admixture air vent in left head area and rear passenger compartment

 Adjustment wheel for air admixture air vent in right head area and rear passenger compartment

 Adjustment wheel for right center nozzle

 Adjustment wheel for right side air outlet

Fresh air mode

Fresh air mode is selected if the LED in the air recirculation mode and air distribution rotary switch is not lit. In fresh air mode, the fresh air and air recirculation flap is opened in the fresh air position by the recirculated air solenoid valve (Y95). In this position, the ambient air in the heater housing is drawn in with help of the front blower motor through the right air inlet in the engine hood and the fresh air and air recirculation flap. Depending on the position of the blower knurled wheel switch, the temperature selection switch and the air recirculation mode and air distribution rotary switch, the fresh air is then routed through the air ducts and the air outlets into the vehicle interior.

Recirculated air mode

Air recirculation mode is selected if the LED in the air recirculation mode and air distribution rotary switch is lit. In air recirculation mode, the fresh air and air recirculation flap is closed in the recirculated air position by the recirculated air solenoid valve. In this position, the recirculated air is drawn in from the vehicle interior into the heater housing with help of the front blower motor. Depending on the position of the blower knurled wheel switch, the temperature selection switch and the air recirculation mode and air distribution rotary switch, the recirculated air is then routed through the air ducts and the air outlets back into the vehicle interior.