Mercedes-Benz ML320. Manual — part 671

Fig. 62: Identifying Evaporator Housing Function - Operating Condition Blend Air Ducting
(Warm/Cold) Closed-Loop Operation

Operating condition: Blend air (warm/cold) Function

In the blend air operating status, the fresh air (A) is drawn in by the blower (5) into the evaporator housing and
routed through the dust filter (3). The air purified by the dust filter (3) is then routed through the evaporator (2)
and dried there. Some of the dried, cold and cleaned air (B) is routed through the heat exchanger (1) and some is
routed around the heat exchanger (1). This air conduction is controlled via the central setting of the blending air
flaps (6).

The air (B), which has been dried, cooled and cleaned by the heat exchanger (1) is heated up again. After
passing through the blending air flaps (6) this heated air (C) is mixed up to form blend air (D) with the dried,
cooled and cleaned air, which was routed around the heat exchanger (1). This blend air (D) is then routed via
the air outlets (E, F, M and S) into the passenger compartment. The recirculated air flap (4) is closed.

Operating condition: Air ducting "recirculation air" in cooling mode

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

Fig. 63: Identifying Evaporator Housing Function - Operating Condition Air Ducting Recirculation Air
In Cooling Mode)

Operating condition: Cooling down "recirculation air" Function

In the cooling mode with recirculating air the blower (5) draws the recirculated air (A) from the passenger
compartment over the opened recirculated air flaps (4) into the evaporator housing and routes it through the dust
cleaner (3). The air purified by the dust filter (3) is then routed through the evaporator (2) and dried there. The
fresh air (B), which has been dried, cooled and cleaned, is subsequently routed around the heat exchanger (1).
This air conduction is controlled via the setting of the blending air flap (6).

The dried, cooled and cleaned air (B) is routed directly into the passenger compartment via the air outlets (E, F,
M and S). The supply of fresh air is cut off by the recirculated air flap (4).

EVAPORATOR HOUSING, TASK - GF83.30-P-2104-04GH

The evaporator housing houses the following components:



Air ducting flaps



Dust filter



Blower



Series resistor group



Evaporator



Heating system heat exchanger



Expansion valve

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me



Blending air flap actuator



Recirculated air flap actuator motor



Electric heater booster (for engine 612.963 only) and therefore forms a complete unit.

The evaporator housing distributes the air that is required to ventilate the vehicle to the relevant air ducts and
vents depending on the required interior temperature.

The air ducting depends on various operating conditions such as:



Heating mode



Cooling mode



Blend air mode (cold/warm)



Cooling air mode with recirculated air

FRESH AIR/RECIRCULATED AIR FLAP ACTUATOR MOTOR, POSITION - GF83.30-P-2105-01GC

The fresh air/recirculated air flap actuator motor (M16/7) is located on the A/C housing between the two fresh
air/recirculated air flaps.

Fig. 64: Identifying Fresh Air/Recirculated Air Flap Actuator Motor

FRESH AIR/RECIRCULATED AIR FLAP ACTUATOR MOTOR, POSITION - GF83.30-P-2105-01GH

The fresh air/recirculated air flap actuator motor (M39) is located at the side of the air intake housing on the
evaporator housing.

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

Fig. 65: Identifying Fresh Air/Recirculated Air Flap Actuator Motor

FRESH AIR/RECIRCULATED AIR FLAP ACTUATOR MOTOR, FUNCTION - GF83.30-P-2105-02GH

Function

The fresh air/recirculated air flap actuator motor (M39) is controlled via the recirculation air switch (

) and

when the temperature selector switch is set to max. cooling output in the control module (S98).

Recirculated air mode (100 % recirculated air)

In the recirculated air mode the supply of fresh air is closed by the fresh air/recirculated air flap actuator motor
(M39) and simultaneously the recirculated air supply opened without any time limit.

Fresh air mode (100 % fresh air)

In the fresh air mode the supply of fresh air is opened by the fresh air/ recirculated air flap actuator motor (M39)
and simultaneously the recirculated air supply closed without any time limit.

Auxiliary function at air conditioning (TAC)

When, in the cooling mode, the temperature selector wheel is set to max. cooling (position indented blue) then
at the same time the fresh air/recirculated air flap actuator motor (M39) is controlled and switched to
recirculation air without time limit.

FRESH AIR/RECIRCULATED AIR FLAP ACTUATOR, FUNCTION - GF83.30-P-2105-02GI

Function

Pressing the recirculating air push-button (

) on the AAC push-button control module (N22) actuates the

fresh air/recirculated air flap actuator motor (M2/5) via the air conditioner bus.

In recirculation mode, the recirculation air supply is closed off by the fresh air/recirculated air flap.

In fresh air mode, the fresh air supply is opened by the fresh air/ recirculated air flap.

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me