Content .. 653 654 655 656 ..

Mercedes-Benz ML320. Service manual - part 655

Fig. 2: Identifying Ventilation Function - Air Distribution Duct

Function

The ventilation system ensures:



that the windshield and windows are kept without mist.



that there is a supply of fresh air to the vehicle occupants.



that constant and pleasant temperatures are quickly achieved in the vehicle interior.

Ventilation is achieved with the assistance of the blower motor during normal operation, when vehicle is
stationary or to increase the air quantity.

Fresh air is drawn into the evaporator housing via the air inlet. Depending on the automatic air conditioning
push-button control module setting, the air is directed through the air ducts to the air vents in the interior.

The air flows out of the vehicle again through the rear vent via ventilation slots to the left and right in the area
below the rear side windows.

In recirculation mode, air is drawn out from the vehicle interior via the fresh air/recirculation flap (recirculation
setting) by the blower motor and passed to the evaporator housing.

The ventilation is essentially divided into heating operation and cooling operation.

Heating operation

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

Two main objectives are pursued in heating operation:



rapid heating and even control of in-car temperature



good visibility through windshield and front side windows

In the starting phase the headroom temperature is deliberately increased, in order to meet the passengers' initial
increased heat requirements. The temperature and the duration depend on the outside temperature and the in-car
temperature.

As far as good visibility is concerned, special control measures to accelerate defrosting of the windows are
taken during the starting phase, depending on the ambient conditions.

In closed-loop operation the footwell vents are mainly used to control the in-car temperature. The center nozzle
is fully closed. The defrosting control measures are reduced.

Cooling operation

During cooling operation the objective is to cool the interior rapidly and evenly control the temperature.

Window fogging is not usually a problem during maximum cooling operation and therefore does not require
special measures.

In the starting phase the headroom temperature is deliberately reduced. The temperature and the duration
depend on the outside temperature and the in-car temperature.

Furthermore, the cooling capacity can be reduced during subsequent operation since continuous partial
recirculating air operation can be achieved.

In closed-loop operation the center nozzles are mainly used to control the in-car temperature.

Bi-level operation (2-level operation)

In bi-level operation the temperature of the interior is controlled by a combination of the footwell nozzles and
the center nozzles.

The objective is to create stratification , which gives the passengers warm feet and a cooler head .

The air distribution shifts in the direction of heating or cooling operation depending on the controller status
trend.

Rear compartment ventilation

The rear compartment nozzles are supplied with temperature-controlled air by the front compartment automatic
air conditioning. The rear compartment nozzle outlet temperature can therefore not be separately controlled.

The air quantity and the air distribution are available as adjustable parameters. The passengers in the rear can
control the ventilation themselves using appropriate buttons.

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

In automatic mode the air quantity and the air distribution are controlled depending on the status of the
automatic air conditioning.

AIR INLET, LOCATION - GF83.10-P-2100-01GH

The air inlet (1) is located at the bottom of the windshield.

Air inlet, location/function

GF83.10-P-2138GC

Air ducts, location/task/design

GF83.10-P-2139GH

Rear vent, location/task/function

GF83.10-P-2143GC

Defroster vent, location/task/function

GF83.10-P-2144GC

Center nozzle, location/task/function

GF83.10-P-2149GC

Lateral nozzle, location/task/function

GF83.10-P-2150GC

Rear nozzle position/task//function

GF83.10-P-2151GI

Front footwell air outlet, location/task/function

GF83.10-P-2145GC

Rear footwell air outlet, location/task/function

GF83.10-P-2146GI

Blower motor, position/task//function

GF83.10-P-2170GI

Rear blower motor, position/task/design/function

GF83.10-P-2168GI

Blower regulator, location / task / function

GF83.10-P-2141GI

Rear ventilation electronic blower regulator location/task/function

GF83.10-P-2176GI

Combination filter, location/task/function

GF83.10-P-2128GI

Defroster vent flap actuator motor, location/task/ function

GF83.10-P-2175GI

Footwell flap actuator motor, location / task / function

GF83.10-P-2132GI

Center outlet flap actuator motor, location / task / function

GF83.10-P-2172GI

Rear shutoff flap actuator motor, location / task / function

GF83.10-P-2171GI

Rear air distribution flap actuator motor, location / task / function

GF83.10-P-2173GI

Fresh air/recirculation flap, location / task / function

GF83.20-P-2111GC

Fresh air/recirculation flap actuator motor, location / task / function

GF83.30-P-2116GC

Blending air flap actuator motor, location / task / function

GF83.57-P-2112GI

Blower switch, location/task/design/function

GF83.25-P-2100GI

Air distribution switch, location/task/design/ function

GF83.25-P-2101GI

Recirculating air push-button, location/task/ function

GF83.40-P-2145GI

Air conditioner housing, location / task / design / function

GF83.40-P-2105GI

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

Fig. 3: Identifying Air Inlet

AIR DUCT LOCATIONS - GF83.10-P-2101-01GH

The lateral nozzle and side window defroster nozzle (3) air ducts are on the left and right below the instrument
panel.

The windshield defroster nozzle air duct (2) is on top of the heater/evaporator housing (front center) below the
instrument panel.

The center nozzle air duct (1) is on top of the heater box/evaporator housing behind the center nozzle.

The front footwell air duct (4) is integrated in the heater/evaporator housing.

The rear footwell air duct (5) is below the center console.

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

Content .. 653 654 655 656 ..