Ventilation system function

N83.10-2043-05

Shown with code (H13) Additional heat exchanger in passenger compartment

1 Defroster vent for left side window

2 Adjustable left side air outlet

3 Thumb wheel for left side air outlet

4 Adjustable left center nozzle

5 Thumb wheel for air supply for air vents in left and right head area and rear compartment

5/1 Air vents for left head area and rear compartment

5/2 Air vents for right head area and rear compartment

6 Adjustable right center nozzle

7 Thumb wheel for right side air outlet

8 Adjustable right side air outlet

9 Defroster vent for right side window

10 Thumb wheel for left center nozzle

11 Thumb wheel for right center nozzle

18/1 Blower switch

18/2 Temperature selection switch

18/3 Air distribution switch

N18 Heater operating unit

N18s1 Rear heater switch

N18s2 Air recirculation switch

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

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Aeration can occur using one of the following two modes:

 Fresh air mode

 Air recirculation mode

Selection is made using the air recirculation switch (N18s2). The air flow control (18/1) and air distribution switch (18/3) which are integrated in the heater operating unit (N18), are used to regulate the rate of circulation and distribution of fresh or recirculated air. The air flow control (18/1) adjusts the output of the blower motor (M2) to regulate the rate of circulation.

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In order to control the rate of circulation, the air flow control (18/1) can be used to adjust the blower motor (M2) output in the following 6 stages by way of the blower motor series resistor group (R14):

 STAGE 0

 Stage 1

 STAGE 2

 STAGE 3

 STAGE 4

 STAGE 5

Distribution of the aspirated fresh or recirculated air can be regulated via the air distribution flap using the air distribution switch (18/3). The distribution of the suctioned fresh or recirculated air is possible in the following positions:

 Defroster vents (12:00 o'clock position)

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

 Footwell vents (6 o'clock position)

 Dash support vents (9 o'clock position)

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 Apart from the positions listed here, intermediate positions are also possible, e.g. if the air distribution switch (18/3) is set between the defroster vents position (12 o'clock position) and the defroster vents and footwell vents
(3 o'clock position).

Distribution of the aspirated fresh or recirculated air in the vehicle interior is then performed depending on the position of the air distribution switch (18/3), via the following air outlets:

 Defroster vent for left side window (1)

 Adjustable left side air outlet (2)

 Adjustable left center nozzle (4)

 Air vents for left head area and rear compartment (5/1)

 Air vents for right head area and rear compartment (5/2)

 Adjustable right center nozzle (6)

 Adjustable right side air outlet (8)

 Defroster vent for right side window (9)

 Right and left footwell air outlets

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 Outlet of fresh or recirculated air is also dependent on the position of the following thumb wheels:

 Thumb wheel for left side air outlet (3)

 Thumb wheel for air addition at vents for left and right head and rear areas (5)

 Thumb wheel for right side air outlet (7)

 Thumb wheel for left center air outlet (10)

 Thumb wheel for right center air outlet (11)

Fresh air mode

The fresh air mode is selected when the red light emitting diode (LED) in the air recirculation switch (N18s2) is not on. During fresh air mode, the fresh air/air recirculation flap actuator motor (M16/21) keeps the two fresh air and air recirculation flaps open in the fresh air position. In this position, the blower motor (M2) is used to suck in the ambient air into the heater housing via the air inlet above the hood, the particulate filter (on vehicles with code (HF2) Pollen filter) and over the two fresh air and air recirculation flaps.

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Depending on the position of the air flow control (18/1), the temperature selector switch (18/2) and air distribution switch (18/3), fresh air then flows through the air ducts and air outlets into the vehicle interior. The fresh air escapes through the two vent flaps from the vehicle, which are attached to the left rear side wall and to the right rear side wall.

Recirculation mode

The air recirculation mode is selected when the red LED in the air recirculation switch (N18s2) is on. During air recirculation mode, the fresh air/air recirculation flap actuator motor (M16/21) keeps the two fresh air and air recirculation flaps closed in the recirculated air position. In this position, the blower motor (M2) is used to suck the recirculated air out of the vehicle interior into the heater housing. Depending on the position of the air flow control (18/1), of the temperature selector switch (18/2) and of the air distribution switch (18/3), the recirculated air then flows through the air ducts and air outlets into the vehicle interior.

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Air recirculation switch (N18s2) convenience feature

If the air recirculation switch (N18s2) is pressed for longer than
1.5 s, the convenience closing feature is triggered. In doing so, the following windows and tilting/sliding roofs are closed and their particular position before they are closed is stored:

 Side windows of driver and front passenger door

 Rear tilting/sliding roof (SHD) (M12/1), with code (D24) Glass tilting/sliding roof in passenger compartment

 Tilting/sliding roof (SHD) (M12), with code (D27) Glass tilting/sliding roof, driver compartment

If the air recirculation switch (N18s2) is pressed again for longer than 1.5 s, then the listed windows and sliding roofs are moved to their previously stored positions again.