Ventilation system, function

D83.10-1137-05

Shown with code (H13) Additional heat exchanger in load compartment, with code (HH7) Additional air conditioning in rear or with code (H08) High-performance air conditioning

1 Defroster outlet for left side window

2 Adjustable left side air outlet

3 Adjustment wheel for left side air outlet

4 Adjustable left center nozzle

5 Adjustment wheel for left center nozzle

6 Air vent for left head area and rear passenger compartment

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

8 Air vent for right head area and rear passenger compartment

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

10 Adjustable right center nozzle

11 Adjustment wheel for right center nozzle

12 Adjustment wheel for right side air outlet

13 Adjustable right side air outlet

14 Defroster outlet for right side window

S98 KLA control and operating unit

D83.40-1114-11

Body shown with code (H13) Additional heat exchanger in load compartment, with code (HH7) Additional air conditioning in rear or with code (H08) High-performance air conditioning

S98 KLA control and operating unit

S98s6 Air recirculation mode button

S98s8 Air distribution switch

S98s10 Blower control button (+)

S98s11 Blower control button (-)

S98s14 Temperature selection switch

The vents supply air to the vehicle interior (air circulation) and additionally ensure 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

 Air recirculation mode

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 Air recirculation mode is terminated after 10 to 30 min. dependent upon the outside temperature. Next, the system automatically switches back to fresh air mode.

Fresh air mode or air recirculation mode can be selected using the air recirculation mode button. The blower control button (+), blower control button (-) and the air distribution switch, which are integrated into the KLA control and operating unit, are used to regulate the rate of circulation and distribution of fresh or recirculated air.

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The rate of circulation is regulated using the blower control button (+) which increases blower motor (M2) output, and the blower control button (-) which reduces it. The blower control button (+) and blower control button (-) can be used to regulate the rate of circulation by setting the blower motor output to the following 5 stages using the blower regulator (M2n1):

 Stage 0

 Stage 1

 Stage 2

 Stage 3

 Stage 4

The distribution of the aspirated fresh or recirculated air can be regulated using the air distribution switch which controls the air distribution flaps via the actuator motor for air distribution (M16/22).

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The distribution of the suctioned fresh or recirculated air is possible in the following positions:

 Defroster vents (12 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)

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

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The aspirated fresh air or recirculated air is then distributed in the vehicle interior depending on the position of the air distribution switch via the following air outlets:

 Defroster outlet for left side window

 Adjustable left side air outlet

 Adjustable left center nozzle

 Air vent for left head area and rear passenger compartment

 Air vent for right head area and rear passenger compartment

 Adjustable right center nozzle

 Adjustable right side air outlet

 Defroster outlet for right side window

 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 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

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Fresh air mode

The fresh air mode is active when the red light emitting diode (LED) in the air recirculation mode button is not on. In the fresh air mode, the fresh air/air recirculation flap actuator motor (M16/21) keeps the fresh air and air recirculation flap open in the fresh air position. In this position, ambient air is drawn into the AC housing with the aid of the blower motor over the air inlet above the engine hood, the particulate filter and the fresh air and air recirculation flap. Depending on the setting of the blower control button (+) and the blower control button (-) and depending on the setting of the temperature selection switch and the air distribution switch, fresh air is then routed through the air ducts and air outlets into the vehicle interior. On model 906.6/7, fresh air escapes from the vehicle through the two vent flaps integrated into the left rear D-pillar and in the right rear D-pillar. On model 906.1/2, the vent flaps, through which the fresh air escapes, are mounted in the cab rear wall.

Air recirculation mode

The air recirculation mode is active when the red LED in the air recirculation mode button lights up. In air recirculation mode the fresh air/air recirculation flap actuator motor keeps the fresh air and air recirculation flap in the recirculated air position. In this position, recirculated air is drawn from the vehicle interior into the front AC housing with the aid of the blower motor.

Depending on the setting of the blower control button (+) and the blower control button (-) and depending on the setting of the temperature selection switch and the air distribution switch, recirculated air is then routed through the air ducts and air outlets into the vehicle interior.

 If the outside temperature is above 20 °C, the system automatically switches to fresh air mode after 30 min.

If the outside temperature is below 20 °C, the system automatically switches to fresh air mode after 10 min.