refrigerant type MERCEDES-BENZ ML320 1997 Complete Repair Manual

2000-01 MANUAL A/C-HEATER SYSTEMS
ML 320, ML 430 & ML 55
SPECIFICATIONS
SPECIFICATIONS
DESCRIPTION & OPERATION
A/C CONTROL PANEL
The A/C control panel contains switches to control A/C functions such as blower motor speed, mode control,
i
n-vehicle temperature, A/C on/off, and fresh/recirculated air control. See Fig. 1.
ApplicationSpecification
Compressor TypeNippondenso 7SB16 7-Cyl.
Compressor Belt Tension(1)
Compressor Oil Capacity(2) 5.6-6.3 ozs.
Refrigerant (R-134a) Capacity26.4 ozs.
System Operating Pressures(3)
(1)Belt tension is automatically adjusted by belt tensioner.
(2)Use Densooil 8 (A 001 989 08 03).
(3)Information is not available from manufacturer.
WARNING:To avoid injury from Accidental air bag deployment, read and carefully
follow all SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR
BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY article in
GENERAL SERVICING.

2001 Mercedes-Benz ML320
2000-01 MANUAL A/C-HEATER SYSTEMS ML 320, ML 430 & ML 55

2001 Mercedes-Benz ML320
2000-01 MANUAL A/C-HEATER SYSTEMS ML 320, ML 430 & ML 55
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1998-2005 HVAC
Climate Control - 163 Chassis
GENERAL INFORMATION
GENERAL NOTES: PASSENGER CARS: CLIMATE CONTROL - AH83.00-Z-9999AZ
MODEL all
Notes on retrofitting an air conditioning
systemMODEL allAH83.30-P-
0001-02A
Repair work for defective refrigerant
circuitMODEL allAH83.30-P-
1782-01A
Instructions for installing actuator motorsMODEL 199,230.4AH83.10-P-
0001-01R
Notes on EU type approval requirementsMODEL 170,209,211,220...AH83.70-P-
0001-09Q
Notes on repairing stationary heaterMODEL 202 up to 31.5.97 retrofitted
stationary heaterAH83.70-P-
0001-03D
Information on repairs to stationary heaterMODEL 202 as of 1.6.97, 208 Retrofitted
Thermo Top C stationary heaterAH83.70-P-
0001-03E
Notes on repairing TelestartMODEL 163, 168, 170, 202, 208, 210 ...AH83.70-P-
0003-02AA
Notes on installation of stationary heaterMODEL 215 Retrofitted stationary feelingAH83.70-P-
0008-02N
Notes on handling refrigerant R134aMODEL all Air conditioning system with
cold means R134aAH83.30-N-
0003-01A
Notes on stationary ventilation with
TelestartMODEL 210.### 1# with Telestart T70 for
un-networked heaterAH83.70-P-
0009-01B
Information on installing actuator motorsMODEL 211AH83.10-P-
0001-01T
Information on installing actuator motorsMODEL 219.3AH83.10-P-
0001-01TX
Notes on handling refrigerant R134aMODEL 240AH83.30-P-
0003-01H
Notes on handling refrigerant R134aMODEL 199AH83.30-P-
0003-01SLR
Notes on repairing the stationary heaterMODEL 163.###1# up to 31.8.01
Retrofitted Thermo Top C stationary heaterAH83.70-P-
0001-03A
Notes on repairing stationary heaterMODEL 168 Retrofitted Thermo Top C
stationary heaterAH83.70-P-
0001-03B
Information on repairs to stationary heaterMODEL 170.435/445/447 up to 31.1.00
Retrofitted Thermo Top C stationary heaterAH83.70-P-
0001-03C
AH83.70-P-

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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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 typeas of 1.12.99BT83.57-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
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The control module integrated in the AAC push-button control module (N22) looks after all system regulation
and control functions such as:
comparing preselected and actual temperatures and controlling the air temperature at the air outlets
automatic switchover from fresh air to recirculated air mode
electrical control of refrigerant compressor
controlling the auxiliary fan or the electric suction-type fan motor/ air conditioning with integrated
control
The AAC push-button control module (N22) has a diagnostic capability. Consequently, any faults which occur
are stored in the fault memory which can be read with the help of the diagnosis assistant system (DAS).
When the AAC push-button control module is replaced (N22), variant coding must be carried out using the
Diagnosis Assistant System (DAS).
The AAC push-button control module (N22) also performs the following actuations:
direct: refrigerant compressor; heating water circulation pump; PTC heater booster (OM 612 only), rear
window heater
via the CAN BUS: auxiliary fan, electric suction-type fan motor/air conditioning with integrated control,
blower control and air distribution in the rear compartment (automatic mode)
via the AC bus: blower motor; 8 stepping motors for air distribution
The following sensor signals are read in by the AAC push-button control module (N22):
direct: temperature sensor evaporator, pressure and temperature sensor refrigerant, in-car temperature
sensor, center nozzle vent air temperature sensor, footwell and rear passenger compartment, sun sensor
via the CAN BUS: Ambient temperature display temperature sensor, sensor for specified values in rear
control panel
REFRIGERANT CIRCUIT FUNCTION - GF83.40-P-2001GH
MODEL 163 up to 31.8.01 with CODE (580) Air conditioning or Tempmatic for USA
Blower switch, location/task/design/function GF83.25-P-2100GI
Temperature selector wheel, location/task/ design/function GF83.25-P-2102GI
Air distribution switch, location/task/design/ function GF83.25-P-2101GI
Defroster button, location/task/function GF83.40-P-2139GI
Recirculating air push-button, location/task/ function GF83.40-P-2145GI
Auto button, location/task/function GF83.40-P-2147GI
AC OFF button, location/task/function GF83.40-P-2107GI
Rest push-button, location/task/function GF83.40-P-2148GI
Rear passenger compartment air distribution button, location/task/function GF83.40-P-2173GI

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1998-2005 HVAC Climate Control - 163 Chassis
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Fig. 81: Identifying Condenser
EVAPORATOR, FUNCTION - GF83.40-P-2121-01GC
Function
The refrigerant, which is under high pressure, is injected into the evaporator. The evaporator is a disk-type
evaporator made of soldered semicircular disks with louvered corrugated fins by the Valeo company for model
168 and the Denso company for model 163.
The heat that is required for evaporation is extracted from the air flowing past the evaporator, which cools
down. The soldered semicircular disks with louvered corrugated fins or slats provide a large evaporation surface
and guarantee rapid heat exchange.
The moisture that condenses when the air cools is led to the outside via condensation drain hoses.
The condensation also binds the solids in the air and therefore cleans it.
EVAPORATOR, LOCATION - GF83.40-P-2121-02GH
The evaporator (1) is located in the air conditioning box.

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1998-2005 HVAC Climate Control - 163 Chassis
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Fig. 82: Locating Evaporator
EVAPORATOR, LOCATION/PURPOSE/DESIGN/FUNCTION - GF83.40-P-2121GC
MODELS 163, up to 31.8.01, 168 with code (580) Air conditioning or Tempmatic for USA
MODELS 163 as of 1.9.01 with code (580a) Automatic air conditioning
FLUID RESERVOIR FUNCTION - GF83.40-P-2122-01GI
Function
The liquefied refrigerant enters the fluid reservoir under pressure and flows through a stainless-steel fabric layer
to the filter block. The filter block's pores are matched exactly to the molecular size of the refrigerant. Thus the
refrigerant can flow through the filter block.
All other matter, primarily water, is held back by this molecular filter and deposited. The cleansed refrigerant
then flows through a rising pipe to the expansion valve.
Evaporator,
locationModel 168GF83.40-P-2121-
02GC
Model 163GF83.40-P-2121-
02GH
Evaporator,
purposeThe evaporator is used to cool, dehumidify and clean the interior
air.
Evaporator,
designThe evaporator is a disk-type evaporator made of soldered
semicircular disks with louvered corrugated fins.
Evaporator,
function GF83.40-P-2121-
01GC

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1998-2005 HVAC Climate Control - 163 Chassis
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The refrigerant pressure and temperature sensor (B12/2) operates in a temperature value range of from -10°C to
+90°C.
Cut-in of electric suction-type fan for engine and AC with integrated control (M4/7)
At the following values the electric suction-type fan for engine and AC with integrated control (M4/7) is
actuated:
refrigerant pressure < 14 bar = fan OFF
Refrigerant pressure > 20 bar = fan ON (100 %)
refrigerant pressure 14 to 20 bar = Continuous linear increase in fan speed (20 -100 %)
REFRIGERANT PRESSURE AND TEMPERATURE SENSOR POSITION/TASK/FUNCTION - GF83.40-P-2171GI
MODEL 163 as of 01.09.01 with CODE (580a) Automatic air conditioning
Fig. 95: Identifying Refrigerant Pressure And Temperature Sensor


Refrigerant pressure
and temperature sensor,
locationThe refrigerant pressure sensor (B12/2) is located at the front left
in the engine compartment at the high-pressure line (8) between
the refrigerant compressor (A9) and the capacitor (7).


Refrigerant pressure
and temperature sensor,
taskThe refrigerant pressure and temperature sensor (B12/1) detects
the refrigerant pressure and the refrigerant temperature and sends
these values to the AAC push-button control module (N22).

Refrigerant pressure

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1998-2005 HVAC Climate Control - 163 Chassis
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ENGINE AND AC ELECTRIC SUCTION FAN WITH INTEGRATED CONTROL, FUNCTION - GF83.40-P-2172-01GI
Function
Depending on the refrigerant pressure and/or on the coolant temperature the speed of the engine and AC electric
suction fan with integrated control (M4/7) is increased infinitely.
The engine and AC electric suction fan with integrated control (M4/7) receives the coolant temperature from the
coolant temperature sensor (B11/4) and the refrigerant pressure from the refrigerant pressure and temperature
sensor (B12/2).
This input information is compared by the engine and AC electric suction fan with integrated control (M4/7)
with the stored values and, if necessary, the speed of the engine and AC electric suction fan is increased to 100
%
The engine and AC electric suction fan with integrated control (M4/7) operates with AC switched on and in the
reheat mode for basic ventilation with a capacity of up to 20 %.
The basic ventilation can be switched off under the following conditions:
At an outside temperature of < or = 15°C.
The pressure-dependent fan speed remains the same.
At a driving speed of > 75 km/h.
The pressure-dependent fan speed remains the same.
An overrun time of 60 s can be set in order to ensure that the engine and AC electric suction fan with integrated
control (M4/7) will continue to operate even where the refrigerant compressor is temporarily switched off by
the icing protection.
The engine and AC electric suction fan with integrated control (M4/7) has a power rating of 850 W.
ELECTRIC SUCTION-TYPE FAN FOR ENGINE AND AC WITH INTEGRATED CONTROL, LOCATION/TASK/FUNCTION
- GF83.40-P-2172GI
MODEL 163 as of 1.9.01 with ENGINE 113.965 /981, 612.963, 628.963 with CODE (580a) Automatic air
conditioning
MODEL 163 as of 1.9.01 up to 31.8.02 with ENGINE 113.942 with CODE (580a) Automatic air
conditioning
and temperature sensor,
function GF83.40-P-
2171-01GI

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1998-2005 HVAC Climate Control - 163 Chassis
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Fig. 96: Identifying Electric Suction-Type Fan For Engine And AC With Integrated Control
BUTTON FOR REAR AREA AIR DISTRIBUTION, LOCATION/TASK/FUNCTION - GF83.40-P-2173GI
MODEL 163 as of 01.09.01 with CODE (580a) Automatic air conditioning

Electric suction-type fan for
engine and AC with integrated
control, location


Electric suction-type fan for
engine and AC with integrated
control, taskThe electric suction-type fan for engine and AC with
integrated control (M4/7) is used to cool down the
coolant and the refrigerant.


Electric suction-type fan for
engine and AC with integrated
control, function
GF83.40-P-
2172-01GI

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1998-2005 HVAC Climate Control - 163 Chassis
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