Mercedes-Benz ML320. Manual — part 668

TEMPERATURE SELECTOR WHEEL, LOCATION/TASK/DESIGN/FUNCTION - GF83.25-P-2102GI

MODEL 163 as of 1.9.01 with code (580a) Automatic air conditioning

Fig. 49: Identifying Temperature Selector Wheel - Model 163 As Of 1.9.01 With Code (580a) Automatic
Air Conditioning

AIR CONDITIONING (TAC) FUNCTION - GF83.30-P-0001GH

MODEL 163 up to 31.8.01 with CODE (580) Air conditioning or Tempmatic for USA

Function

The air conditioning's electronically controlled cooling, heating and ventilation system keeps the desired in-car
temperature constant. AC button (

) pressed (illuminates).

wheel, task

temperature desired in the vehicle interior.

Temperature selector
wheel design

Heater:
Rotary switch with disk cam, pivot, control-sleeve levers, as well
as micro stops and end stops Air conditioning Rotary switch with
potentiometer

Temperature selector
wheel, function

Model 168

GF83.25-P-
2102-01GC

Model 163

GF83.25-P-
2102-01GH

Temperature selector
wheel, location

The temperature selector wheel (2) is located in the center in the
AAC push-button control module (N22).

Temperature selector
wheel, task

The temperature selector wheel (2) serves to preselect the
temperature desired in the vehicle interior.

Temperature selector
wheel design

The temperature selector wheel (2) is equipped with a rotary ring,
with which the temperature values can be set. The LEDs in the
rotary ring display the set temperature level.

Temperature selector
wheel, function

GF83.25-P-
2102-01GI

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

After starting, the refrigerant compressor starts up. If cooling is not necessary, the refrigerant compressor's
output is lowered and switched off via the icing inhibitor.

The air conditioning is always ready for operation after the engine has been started, and operates according to
the so-called "reheat" principle. This means: The refrigerant compressor always operates at an ambient
temperature in excess of 1°C, therefore also cools cold incoming air. Following the cooling process, the dried
air is heated at the heat exchanger.

On the one hand, this effect serves the purpose of comfort, because cooling also simultaneously causes air
dehumidification which, in turn, is an important prerequisite for a pleasant interior climate. On the other hand,
the air is dried as a result of this cooling and heating, thereby preventing window fogging.

Pressing the AC button again (

) (does not illuminate) switches off the cooling.

Heating mode

The in-car temperature sensor measures the air temperature in the interior of the vehicle.

The air conditioning control module electronics compares the in-car temperature with the desired temperature
which has been set at the temperature selector wheels.

The microprocessor adjusts the air conditioning electronics or keeps the relevant setting constant as required.

Heater operation with heater booster in vehicles with engine 612.963 as of 12/99

In vehicles equipped with direct-injection diesel engines, an electrical heater booster is additionally installed in
the evaporator housing downstream of the heat exchanger, in order to compensate any heater output deficit
which exists under certain operating conditions.

The 3 heating elements in the heater booster are supplied with current, whereupon they are heated and they start
to glow. As a result of the structural conditions, it is ensured that the drawn in fresh air flows directly past the
electric heater booster, and is therefore heated.

Cooling mode

The icing inhibitor measures the temperature at the evaporator air outlet, while the interior temperature sensor
determines the relevant in-car temperature.

The air conditioning control module electronics compares the various measured values with the desired
temperature which has been set at the temperature selector wheels.

The microprocessor adjusts the air conditioning or keeps the relevant setting constant as required.

In-car temperature sensor replaced by new type

as of 1.12.99

BT83.57-P-0001-04GH

Ventilation, function

GF83.10-P-2000GH

Heater circuit function

GF83.20-P-2003GH

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

AIR CONDITIONING, LOCATION OF COMPONENTS - GF83.30-P-0003-01GH

Location of components in passenger compartment

Fig. 50: Identifying Air Conditioning Components In Passenger Compartment (1 Of 2)

Location of components in passenger compartment

Air conditioning control module function

GF83.30-P-2001GH

Refrigerant circuit function

GF83.40-P-2001GH

Temperature control, function

GF83.57-P-2000GH

Heater booster (ZUH), function

Engine 612.963 GF83.70-P-0005GH

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

Fig. 51: Identifying Air Conditioning Components In Passenger Compartment (2 Of 2)

Location of components in passenger compartment as of 12/99

Fig. 52: Identifying Air Conditioning Components - Location Of Components In Passenger

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me