Mercedes-Benz ML320. Service manual — part 683

Auto button, location/purpose/function

Rear ventilation operating module

2147GI
GF83.40-P-
2147GJ

AC OFF button, location/purpose/function

GF83.40-P-
2107GI

Residual heat button,
location/purpose/function

GF83.40-P-
2148GI

Rear compartment air distribution button,
location/purpose/function

GF83.40-P-
2173GI

All-activity module,
location/purpose/function

GF54.21-P-
4110GH

Air conditioner housing, location/purpose/
design/function

GF83.40-P-
2105GI

Auxiliary fan, location/purpose/function

Engine 111.977, 112.942, 112.970
with code 580 up to 31.08.01
Engine 112.942, 112.970 with code
580a as of 01.09.01

GF83.40-P-
2162GH

Engine and AC electric suction fan with
integrated control, location/purpose/function

Engine 113.942 with code 580a up to
31.08.01 Engine 113.981, 113.965,
612.963, 628.963, with code 580a as of
01.09.01

GF83.40-P-
2172GI

Condenser, location/purpose/function

GF83.40-P-
2152GC

Evaporator location/purpose/design/function

GF83.40-P-
2121GC

Fluid reservoir, location/purpose/function

GF83.40-P-
2153GI

Expansion valve, location/purpose/design/
function

GF83.40-P-
2123GC

Refrigerant pressure and temperature sensor,
location/purpose/function

GF83.40-P-
2171GI

Refrigerant compressor, location/purpose/
design/function

GF83.55-P-
2100P

Control valve, location/purpose/function

GF83.55-P-
2102P

Belt pulley, location/purpose/design/function

GF83.55-P-
2103P

Pressure relief valve,
location/purpose/function

GF83.55-P-
2104P

In-car temperature sensor location/purpose/
function

GF83.57-P-
2115GI

Ice-up protection temperature sensor,
location/ purpose/function

GF83.57-P-
2113GH

Blending air flap actuator, location/purpose/

GF83.57-P-

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

REFRIGERANT COMPRESSOR, LOCATION - GF83.55-P-2100-01GH

Illustrated up to 31.08.01

The refrigerant compressor (A9) is flanged to the engine at front left

Fig. 98: Identifying Refrigerant Compressor

REFRIGERANT COMPRESSOR, FUNCTION - GF83.55-P-2100-02A

function

2112GI

Ambient air temperature sensor, location/
purpose/function

GF83.57-P-
2119GI

Outlet air temperature sensor, center nozzle,
location/purpose/function

GF83.57-P-
2116GI

Outlet air temperature sensor, front footwell,
location/purpose/function

GF83.57-P-
2117GI

Outlet air temperature sensor rear, location/
purpose/function

GF83.57-P-
2118GI

Sun sensor, location/purpose/function

GF83.57-P-
2111GI

Electric heater booster, location/purpose/
design/function

Engine 612.963

GF83.70-P-
4054GH

Extended activity module, location/purpose/
design

GF54.21-P-
4107GK

CDI control module,
location/purpose/function

GF07.16-P-
3102IA

Table of contents, automatic air conditioning
(AAC) function description

GF83.40-P-
0999GI

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

Refrigerant compressor 7SB16C

Fig. 99: Identifying Refrigerant Compressor 7SB16C Components

Function

After the electromagnetic clutch (A9k1) has produced the frictional connection between the automotive engine
and the refrigerant compressor, the drive shaft (1) drives the swash plate (3). The rotation of the inclined swash
plate (3) causes the pistons (4) to move in strokes. During the intake stroke, refrigerant vapor is sucked in via
the inlet valve (6).

If the piston (4) moves in the counter direction, it delivers the refrigerant vapor via the pressure control valve
(7), with the vapor being compressed and heating up, into the refrigerant line to the capacitor. With refrigerant
compressor, model 7SB16C, the refrigerant vapor acts on the control valve (8.1) in the refrigerant compressor
for volume control.

Volume control in model 7SB16C

With a low engine speed, the efficiency of an air conditioning system is severely reduced by the low number of
working strokes of the refrigerant compressor and the reduced cooling of the refrigerant in the capacitor. In this
situation there is an increase in the thermal load. The refrigerant compressor is therefore designed so that it has
a sufficient delivery rate even at low rotational speeds.

With an increase in the engine speed and the vehicle speed, the thermal load drops and the delivery rate of the
refrigerant compressor increases. To prevent the refrigerant compressor now from consuming unnecessary
engine power and nevertheless to maintain the refrigeration cycle, the refrigerant compressor reduces its power

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me

from a maximum of 100 % to a minimum of 5 %.

Fig. 100: Identifying Refrigerant Compressor, Function - (1 Of 2)

Function

100% power (I)

The conditions for full power are either a constantly low rotational speed or a high thermal load or both. The
high manifold air pressure C causes the control valve to close. This prevents steam from flowing between the
rear opening and the crankcase. There is always some flow through the transfer duct between the crankcase and
the inlet opening. Therefore, in the crankcase there is almost the same pressure B as on the inlet side C . As a
result, the swash plate is moved into the position for maximum volume. The angle between the swash plate and
the vertical is at its greatest. This results in a large stroke.

Power from 100% to 5% output ( II)

If the influencing conditions change in that the thermal load drops or the engine speed increases, the pressure on
the inlet side C drops and allows the control valve to open.

Then compressed refrigerant now flows from the rear opening to the crankcase. The pressure in the crankcase B
increases therefore and causes the swash plate to reduce its angle, which leads to a reduction in power.

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

me