Mercedes-Benz ML320. Manual — part 665

Fig. 37: Identifying Heater Box Function - Operating Condition Heating

Operating condition: Heating Function

In the heating operating status, the fresh air (A) is drawn in by the blower (5) into the heater housing and routed
through the dust filter (3). The fresh air (B), which is cleaned by the dust filter (3), is subsequently conducted
through the heat exchanger (1). This air conduction is controlled via the setting of the blending air flaps (6).

The cleaned fresh air (B) is heated up by the heat exchanger (1). The warm air (C) is conducted via the air
outlets (E, F, M and S) into the vehicle interior.

The recirculated air flap (4) is closed.

Operating condition: No heating

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

Fig. 38: Identifying Heater Box Function - Operating Condition No Heating

Operating condition: No heating Function

In the "no heating" operating status, the fresh air (A) is drawn in by the blower (5) into the heater housing and
routed through the dust filter (3).

The fresh air (B), which is cleaned by the dust filter (3), is subsequently routed around the heat exchanger (1).
This air conduction is controlled via the setting of the blending air flaps (6).

The cleaned fresh air (B) is routed directly into the passenger compartment via the air outlets (E, F, M and S).
The recirculated air flap (4) is closed.

Operating condition: No "recirculated air" heating

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

Fig. 39: Identifying Heater Box Function - Operating Condition No Recirculated Air Heating

Operating condition: No "recirculating air" heating Function

In the no "recirculated air" heating mode the blower (5) draws the recirculated air (A) from the passenger
compartment over the opened recirculated air flaps (4) into the heater housing and routs it through the dust
cleaner (3). The recirculated air (B), which is cleaned by the dust filter (3), is subsequently routed around the
heat exchanger (1). This air conduction is controlled via the setting of the blending air flaps (6).

The cleaned recirculated 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).

HEATER HOUSING TASK - GF83.20-P-2103-03GC

The heater housing serves to house the following components



Air ducting flaps



Dust filter



Blower



Series resistor group



Heating system heat exchanger



PTC heater booster (in model 168 with engines OM 668.940/941 as of 01.03.01)



Fresh air/recirculated air flap actuator (with model 168 as of 01.03.01)

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

and therefore forms a complete unit.

The heater housing distributes the air which is required to ventilate the vehicle interior to the relevant air ducts
and air outlets depending on the temperature desired in the interior.

The air ducting depends on various operating conditions such as:



Heating



No heating



Fresh air mode



Recirculated air mode

FRESH AIR/RECIRCULATED AIR FLAP, LOCATION - GF83.20-P-2104-01GH

The fresh air/recirculated air flap (1) is located at the top of the heater/A/C housing.

Fig. 40: Identifying Fresh Air/Recirculated Air Flap

FRESH AIR/RECIRCULATED AIR FLAP, FUNCTION - GF83.20-P-2104-02GH

Function

The fresh air/recirculated air flap is actuated by the fresh air/ recirculated air flap actuator (M2/5).

Fresh air mode

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me