battery MERCEDES-BENZ ML320 1997 Complete Repair Manual

motor. See Fig. 2 .
PROGRAMMING
RECODING RADIO
1. Turn ignition on. Ensure CODE is displayed on radio display. Enter code numbers using radio station
buttons. For example, use station button No. 1 for code No. 1 and so on.
2. After first number is entered, CODE disappears and number entered is displayed followed by 4 dashes.
After entering 5-digits, confirm correct security code has been entered. If incorrect code has been entered,
entire code must be reentered.
3. Confirm entry of correct security code using "<" (less than) or ">" (more than) buttons. If an incorrect
code is entered, CODE will be displayed on radio display. If security code is entered incorrectly 3 times,
WAIT will be displayed and radio will be disabled for about 10 minutes.
4. If, after 3 more attempts, correct security code has not been entered, radio will be disabled for 60 minutes.
Radio disable time runs down only when radio is turned off.
VERSION CODING
Version coding is performed using a Mercedes-Benz Hand-Held Tester (HHT) and is on-screen menu guided.
After connecting HHT to DLC, vehicle communication is possible as soon as ignition key is inserted into
ignition switch (position of switch does not matter). Version coding menu, position 1, is reached via main menu
and control module adaptation, position 5. There are 2 possible version codings available: readout of version
code and transfer to new control module or readout of version code and to alter code.
To access A/C system version coding, position 2 must be selected and then position 7 for A/C system. Two
selections can be used: A/C system is installed or A/C system is not installed.
SELF-DIAGNOSTICS
RETRIEVING & ERASING DIAGNOSTIC TROUBLE CODES
Retrieving and erasing of Diagnostic Trouble Codes (DTC) must be performed using Mercedes-Benz Hand-
Held Tester (HHT). See HHT instructions for retrieving A/C-heater system related DTC. After noting codes,
see CLIMATE CONTROL DTC
table. To erase DTC, follow HHT instructions.
When retrieving DTC from A/C push button control module, short and open circuits cannot be differentiated
from each other in every instance. When accessing DTC from any control module memory, all stored DTC are
shown. As a result, some DTC shown will not appl
y to climate control system. CAUTION: Before disconnecting battery, obtain 5-digit radio security code from
vehicle owner. Radio will be disabled until properly recoded.
NOTE: Radio will not operate if power supply to radio is interrupted. Obtain 5-digit
radio security code from vehicle owner before disconnecting battery.

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OUTSIDE TEMPERATURE SENSOR RESISTANCE
READING ACTUAL VALUES WITH HHT
Connect Hand-Held Tester (HHT) to DLC and follow displayed procedures. Actual values displayed on HHT
show normal operation value of A/C systems or components. See ACTUAL VALUES
table. If value is not as
specified, check system or components in order. Repair as necessary.
ACTUAL VALUES
REMOVAL & INSTALLATION
Sensor Temperature - °F (°C)Ohms
68 (20)2100
77 (25)1700
104 (40)900
122 (50)600
Step (1) Test ConditionValueSystem/Component
01.....11-14 VoltsVoltage Supply Wiring (Circuit
No. 30) & Battery
02Engine Operating At
Normal TemperatureAbout 176°F (80°C)Wiring, ECT Sensor & AAM
03Ignition ONAmbient Air Temperature
About 68°F (20°C)Wiring, Outside Temperature
Sensor & AAM
04Ignition ON, Blower At
Stage 4ON/OFFWiring, Blower Motor Relay,
Blower Motor & AAM
05Ignition ONON/OFFWiring, Engine Cooling Fan
Stage 1, Aux. Fan & AAM
08Ignition ONON/OFFWiring, Coolant Circulation Pump
Relay, Coolant Circulation Pump
& AAM
09Engine On, A/C Indicator
On, Blower Motor At
Stage 4Refrigerant Pressure At
174 psi (12 bar)(2) Refrigerant Pressure Sensor
10Engine On, A/C Indicator
On, Blower Motor At
Stage 4ON/OFF(3) AAM, A/C Compressor
11Ignition ON, Activate
A/C SystemYES/NOWiring, A/C Push Button Control
Module, AAM
(1)Step numbers not shown are not used.
(2)Check A/C refrigerant pressure switch. See A/C REFRIGERANT PRESSURE SWITCH under
ELECTRICAL TESTS.
(3)Check A/C button activation. See A/C BUTTON under ELECTRICAL TESTS.

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A/C EVAPORATOR HOUSING UNIT
Removal & Installation
1. Drain engine coolant. Remove coolant expansion reservoir nuts, disconnect hoses and remove reservoir.
Discharge A/C system, using approved refrigerant recovery/recycling equipment.
2. Remove expansion valve self-locking nut and discard. See Fig. 5
. Disconnect refrigerant lines from
expansion valve. Plug exposed refrigerant lines to protect A/C system from moisture and debris.
3. Remove instrument panel. See INSTRUMENT PANEL
. Remove Electronic Transmission Control
(ETC) module. See Fig. 4
. Disconnect air mix flap actuator connector.
4. Disconnect recirculated air flap element. Disconnect evaporator temperature sensor. Disconnect blower
motor resistor and blower motor connectors. Remove A/C push button control module. Release wiring
harness.
5. Remove insulating mat. See Fig. 5
. Disconnect water drain hose from bottom of A/C housing. Release
A/C housing-to-air distributor clips and remove A/C housing upward. To install, reverse removal
procedure. Recode radio. See RECODING RADIO
under PROGRAMMING. 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.
CAUTION: Before disconnecting battery, obtain 5-digit radio security code from
vehicle owner. Radio will be disabled until properly recoded.

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Fig. 4: Removing Evaporator Housing Unit
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
A/C MIX FLAP ACTUATOR
Removal & Installation
Remove instrument panel. See INSTRUMENT PANEL . Disconnect air mix flap actuator connector. Remove
3 screws and remove air mix flap actuator. To install reverse removal procedure.
A/C PUSH BUTTON CONTROL MODULE
Removal & Installation
Disconnect negative battery cable. Remove A/C push button control panel. See A/C PUSH BUTTON
CONTROL PANEL . Remove 4 A/C push button control module screws and remove control module from

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A/C housing. Disconnect control module connector. To install reverse removal procedure. Recode 5-digit radio
security code. Using HHT, check for DTC and erase, and set clock.
A/C PUSH BUTTON CONTROL PANEL
Removal & Installation
1. Obtain 5-digit radio security code from vehicle owner. Disconnect negative battery cable. Using radio
removal plates, remove radio. Disconnect electrical connectors.
2. Remove instrument panel center section. Remove 4 A/C control panel screws and remove control panel.
Release pull cables and disconnect connectors. To install, reverse removal procedure. Recode radio. See
RECODING RADIO
under PROGRAMMING.
BLOWER MOTOR
Removal & Installation
Remove passenger-side instrument panel under cover. Remove blower motor mounting screws from A/C
housing unit. Disconnect blower motor connector and remove blower motor. To install, reverse removal
procedure.
COMPRESSOR
Removal & Installation
1. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Remove accessory
drive belt. Disconnect low pressure refrigerant line from compressor. Discard "O" rings. Plug exposed
openings to protect A/C system from debris and moisture.
2. Disconnect high pressure refrigerant line from compressor. Discard "O" rings. Plug exposed openings to
protect A/C system from debris and moisture. Disconnect electrical connector. Remove compressor
mounting bolts.
3. Raise and support vehicle. Remove compressor from under vehicle without spilling refrigerant oil. To
install, reverse removal procedure. Ensure refrigerant oil quantity in compressor is correct. See
COMPRESSOR REFRIGERANT OIL CHECKING under GENERAL SERVICING. Tighten bolts to
specification. See TORQUE SPECIFICATIONS
.
CONDENSER
Removal & Installation
1. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Remove cooling fans.
See COOLING FANS
. Disconnect refrigerant line from receiver-drier. See Fig. 5 . Discard "O" rings.
2. Plug exposed openings to protect A/C system from debris and moisture. Remove refrigerant line from
condenser. Remove radiator upper rubber seal. See Fig. 6
. Remove condenser upper mounting screws.
Lift condenser upward and remove. NOTE: Each time A/C compressor is removed and installed, receiver-drier must be
replaced.

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Fig. 6: Removing Cooling Fans & Condenser
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
COOLING FANS
Removal & Installation
Remove headlight units. Remove upper frame crossmember, release hood release control cable and remove
crossmember. See Fig. 6
. Remove 2 cooling fans frame bolts on radiator. Disconnect cooling fan connector.
Release outside temperature sensor wiring harness. Pull up on cooling fan and remove. To install, reverse
removal procedure. Ensure cooling fan bottom guides are properly seated in lower mounts.
EVAPORATOR
Removal & Installation
Remove A/C housing unit. See A/C HOUSING UNIT . Remove expansion valve. See Fig. 5 . Discard "O"
rings. Disassemble A/C housing unit. Remove evaporator. Remove evaporator temperature sensor. To install,
reverse removal procedure. Use NEW "O" rings lubricated with refrigerant oil. If installing a new or repair
evaporator, add 1.35 ounces of NEW refrigerant oil to evaporator.
EXPANSION VALVE
Removal & Installation
1. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Without disconnecting
coolant hoses, remove coolant expansion reservoir and set aside. Remove refrigerant line bracket and
loosen clamps. See Fig. 5
. Pull refrigerant lines out of expansion valve.
2. Remove expansion valve self-locking nut and discard. Remove expansion valve. Discard "O" rings. To
install, reverse removal procedure. Use NEW "O" rings lubricated with refrigerant oil. Tighten NEW self-
locking nut to specification. See TORQUE SPECIFICATIONS
.
INSTRUMENT PANEL & INSTRUMENT PANEL CARRIER
Removal & Installation
1. Secure vehicle against rolling. Set transmission selector to "D" position. Obtain radio security code.
Disconnect negative battery cable. Remove driver-side air bag.
2. Place match marks on steering wheel and steering shaft. Remove steering wheel, upper steering column
covers and combination switch. Remove instrument cluster cover frame. Remove one instrument panel
lower section bolt.
3. Remove screws in footwell from left side of instrument panel bottom section. Remove instrument panel
center section. Remove 4 A/C control panel screws and remove control panel. See Fig. 1
. Release pull
cables and disconnect connectors.
4. Remove screws from center section. Remove glove box. Remove screws in footwell from right side of
instrument panel bottom section. Remove entry courtesy lights. Remove end covers and screws.
5. Release 4 "A" clips between instrument panel bottom section and upper section. See Fig. 7
. Release
parkin
g brake release cable from handle. With assistance, remove instrument panel bottom section.

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REST BUTTON, FUNCTION - GF83.40-P-2109-01GI
Function
Pressing the reset button ( ) on the AAC push-button control module (N22) switches on the residual engine
heat utilization system. When the engine is switched off, the residual heat heats the vehicle depending on the
temperature setting on the AAC push-button control panel (N22) and the ambient temperature in the vehicle
interior. The vehicle can be heated for approx. 30 min, with the engine switched off. The function is only
available with the ignition switched off or in position 1. If there is low voltage, the residual heat function is
automatically switched off.
The flaps are in automatic mode and the quantity of air is also automatically regulated.
The residual heat function is switched off,
if the electronic key is moved to position 2 in the starter switch,
after approx. 30 minutes,
if the battery voltage drops below 11V.
AUXILIARY FAN, FUNCTION - GF83.40-P-2115-01GH
Function
Depending on the refrigerant pressure and/or the coolant temperature the left auxiliary fan (M4m1), right
auxiliary fan (M4m2) are actuated.
The all-activity module (AAM) (N10) receives the coolant temperature from the coolant temperature sensor and
the refrigerant pressure from the refrigerant pressure sensor (B12).
The all-activity module (AAM) (N10) compares this input information with stored values and actuates the left
auxiliary fan (M4m1), right auxiliary fan (M4m2).
When the following values are indicated the left auxiliary fan (M4m1), right auxiliary fan (M4m2) are switched
on or off:
refrigerant pressure >16 bar = auxiliary fan ON
refrigerant pressure < 12 bar = auxiliary fan OFF
coolant temperature > 105°C = auxiliary fan ON
coolant temperature < 94°C = auxiliary fan OFF
AUXILIARY FAN, FUNCTION - GF83.40-P-2115-01GI
Function
Depending on the refrigerant pressure and/or the coolant temperature the left auxiliary fan (M4m1) and the right
auxiliary fan (M4m2) are actuated.

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Whenever the system is opened, the fluid reservoir should be replaced because of the water which has
collected there in the meantime.
EXPANSION VALVE, FUNCTION - GF83.40-P-2123-01GC
Function
When the refrigerant compressor is switched on the pressure in the evaporator drops, thereby causing the
diaphragm (1) to curve downwards. The control valve (3) follows the movement of the diaphragm and presses
the ball (4) out of its seating against the spring (5). The opened valve enables the refrigerant to be sprayed into
the evaporator.
As the diaphragm movement (1) is dependent on both the intake pressure and the temperature at the evaporator
outlet, only the specific quantity of refrigerant, as required for optimum vaporization, is injected.
Fig. 83: Identifying Expansion Valve Components

EXPANSION VALVE, LOCATION - GF83.40-P-2123-02GH
The expansion valve (1) is located on the right at the rear in the engine compartment next to the battery.

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OFF . To this end the system uses the residual heat of the engine. The residual engine heat is dissipated to the
coolant and routed through the heat exchanger with the aid of the heating water circulation pump. The air drawn
in by the blower motor is routed around the heat exchanger, whereby it is then warmed up. The heated air is
then routed over the air outlets into the passenger compartment.
The residual engine heat utilization system can only be used when the ignition is switched OFF.
Once the Rest push-button ( ) on the AAC push-button control module (N22) has been pressed the
following program sequence is run:
Blending air flaps are automatically controlled
Heating water circulation pump ON
The blower's control voltage is limited to a maximum value of 5 Volt.
End of program
Pressing the Rest push-button ( )
Timeout of 30 minutes period (repeated operation possible)
Protection against undervoltage at a battery voltage of less than 11 V (LED flashes)
Ignition ON
During the residual engine heat utilization function no function keys are accepted apart from the Rest push-
button ( ) and the set point adjusters.
SAFETY PRECAUTIONS
RISK OF EXPLOSION CAUSED BY WELDING OR SOLDERING WORK ON CLOSED AIR CONDITIONING SYSTEM.
RISK OF POISONING CAUSED BY INHALING OVERHEATED REFRIGERANT VAPORS. RISK OF INJURY TO SKIN AND
EYES CAUSED BY CONTACT WITH LIQUID REFRIGERANT. - AS83.00-Z-0001-01A
Never perform welding work on or near a closed air conditioning system. No smoking or open flames.
Wear safety glasses and protective gloves. Work only in well ventilated areas. Carry out repair work on
the air conditioning system circuit only after the system has been discharged.
Potential risks
Risk of explosion
When closed air conditionin
g systems (charged or empty) become heated, high pressures are produced that can
Rest push-button, location/task/function GF83.40-P-2148GI
Heating water circulation pump, location/task/ function GF83.20-P-2109GI
Heating system heat exchanger, location/ purpose/function GF83.20-P-2108GC
Blower motor, location/task/design/function GF83.10-P-2170GI
Blending air flap actuator, location/task/function GF83.57-P-2112GI

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AIR CONDITIONING (TAU) DIAGNOSIS FUNCTION CHECK ACTUAL VALUES - AD83.30-P-3001GH
MODEL 163 with CODE (580) Air conditioning or Tempmatic for USA
5
Recirculated air
mode function switch illuminated
Blower switch on stage 4Blower noise
increases significantly
Cables
Recirculated air
switch
Fresh
air/recirculated air
flap actuator motor
Air conditioning (TAU)
diagnosis previous
knowledge AD83.30-P-2000GH
Connect hand-held tester
(HHT), read out
diagnostic trouble code
memoryModel 163 up to 31.8.01AD00.00-P-2000-03C
Operational check
Test scope Operation /
Requirement Specification Possible cause / Remedy
01
Circuit 30 11-14 VWiring
Battery
02Ignition ON Operating temperature
approx. 80°CWiring
Temperature sensor
Coolant (B11/4)
All-activity module
(N10)
Engine temperature Start engine and warm up
to operating temperature.
03Ignition ON Season-dependent,
approx. 20° CWiring
Temperature sensor
Ambient air (B14)
All-activity module
(N10)
Outside temperature
04Ignition ON ONWiring
F1k21
Blower motor (M2)
All-activity module
(N10)
Blower power supply
relay (F1k21) Blower stage 4FROM
05Ignition ON ONWiring
F1k26
Auxiliary fan (M4) Auxiliary fan relay FROM

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