Page 835 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-134
Air outlet c/o
potentiometer55 Mode selection
damper control
motor potentiometerIgnition switch: ON Damper
positionOpening degree (V)
FA C E A p pr o x . 5
FOOT Approx. 3.75
FOOT/DEF. Approx. 2.5
DEF. Approx. 1.75
Air outlet c/o
potentiometer
(target)56 Target value for
mode selection
damper control
motor potentiometerIgnition switch: ON Damper
positionOpening degree (V)
FA C E A p pr o x . 5
FOOT Approx. 3.75
FOOT/DEF. Approx. 2.5
DEF. Approx. 1.75
In/out air
changeover
damper motor65 Outside/inside air
selection damper
control motorIgnition switch: ON Damper set
positionDamper position
Fresh air
positionFRESH
Air recirculation
positionRECIRC
Front blower fan 68 Blower motor Ignition switch: ON The actual air
volume (blower
motor speed)
corresponds to the
air volume shown on
the diagnostic tool.
Front blower
motor voltage 71 Blower motor Ignition switch: ON The air volume set
by the heater control
corresponds to the
value shown on the
diagnostic tool. (V)
Air conditioning
switch state1 Air conditioning
switchIgnition switch: ON Air conditioning
switch: ONDiagnostic tool
indication: "pressed"
Air conditioning
switch: OFFDiagnostic tool
indication: "release"
Rear defogger
switch state7 Rear window
defogger switchIgnition switch: ON Rear window
defogger
switch: ONDiagnostic tool
indication: "pressed"
Rear window
defogger
switch: OFFDiagnostic tool
indication: "release"
Refrigerant
pressure73 Refrigerant pressure Ignition switch: ON The diagnostic tool
indication is normal MUT-III
DIAGNOSTIC
TOOL DISPLAYITEM
NO.INSPECTION ITEM INSPECTION REQUIREMENT NORMAL VALUE
Page 836 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-135
Temperature
setting23 Temperature setting
actualIgnition switch: ON The actual setting
corresponds with
diagnostic tool
display.
Vehicle speed 26 Actual vehicle speed Ignition switch: ON The vehicle speed
corresponds with
diagnostic tool
display.
A/C compressor
drive request27 Compressor clutch Engine: ON
Compressor:
ONDiagnostic tool
indication: "ON"
Compressor:
OFFDiagnostic tool
indication: "OFF"
Illumination 15 Display lighting Ignition switch: ON
Lights: ON
Diagnostic tool
indication: "ON"
Lights: OFF
Diagnostic tool
indication: "OFF"
Engine speed 23 Actual engine speed Engine: ON The engine speed
corresponds with
diagnostic tool
display.
In/out air select
switch state3 In/out air select
switch Ignition switch: ON In/out air
switch: ONDiagnostic tool
indication: "pressed"
In/out air
switch: OFFDiagnostic tool
indication: "release"
Rear defogger
relay72 Rear defogger relay Ignition switch: ON
Rear defogger:
ONDiagnostic tool
indication: "ON"
Rear defogger:
OFFDiagnostic tool
indication: "OFF" MUT-III
DIAGNOSTIC
TOOL DISPLAYITEM
NO.INSPECTION ITEM INSPECTION REQUIREMENT NORMAL VALUE
Page 837 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-136
ACTUATOR TEST REFERENCEM1554005200133
MUT-III DIAGNOSTIC
TOOL DISPLAYITEM NO. INSPECTION ITEM DRIVE CONTENT
Blower fan: OFF 83 Blower motor OFF
Blower fan: Middle 84 Middle speed
Blower fan: High 85 High speed
Air mix damper motor:
0%42 Air mixing damper control motor Opening degree: approx.
0% (Max cool)
Air mix damper motor:
100%43 Opening degree: approx.
100% (Max hot)
Air outlet c/o damper:
FA C E70 Mode selection damper control
motorFA C E
Air outlet c/o damper: Bi_
Level67 FOOT/FACE
Air outlet c/o damper:
FOOT71 FOOT
Air outlet c/o damper:
DEF/FOOT69 DEF/FOOT
Air outlet c/o damper:
DEF68 DEF
Idle up request: high load 74 Idle speed HIGH idle up
Idle up request: low load 75 LOW idle up
Idle up request: OFF 76 OFF
Rear defogger switch:
OFF40 Rear window defogger switch Rear window defogger: OFF
Rear defogger switch:
ON41 Rear window defogger: ON
Idle up request: OFF 50 Idle up operation Idle up: OFF
Idle up request: low load 51 Idle up: low load
Idle up request: high load 52 Idle up: high load
Condenser: 0% 77 Condenser fan OFF
Condenser: 50% 79 Middle speed
Rheostat: 0% 80 Rheostat- Illumination control OFF
Rheostat: 100% 81 Full duty
Rheostat: 50% 82 Half duty
Page 841 of 1500
SPECIAL TOOLS
HEATER, AIR CONDITIONING AND VENTILATION55-140
A: MB991824
B: MB991827
C: MB991910
D: MB991911
E: MB991914
F: MB991825
G: MB991826
MUT-III Sub
Assembly
A: Vehicle
communicatio
n interface
(V.C.I.)
B: MUT-III USB
cable
C: MUT-III main
harness A
(Vehicles with
CAN
communicatio
n system)
D: MUT-III main
harness B
(Vehicles
without CAN
communicatio
n system)
E: MUT-III main
harness C (for
Daimler
Chrysler
models only)
F: MUT-III
measurement
adapter
G: MUT-III
Trigger
HarnessMB991824-KIT
NOTE: . G:
MB991826 MUT-III
Trigger Harness is not
necessary when
pushing V.C.I.
ENTER key.Checking diagnostic trouble codes
For vehicles with CAN
communication, use MUT-III
main harness A to send
simulated vehicle speed. If you
connect MUT-III main harness B
instead, the CAN
communication does not
function correctly. TOOL TOOL NUMBER
AND NAMESUPERSESSION APPLICATION
Page 861 of 1500
SENSORS
HEATER, AIR CONDITIONING AND VENTILATION55-160
SENSORS
REMOVAL AND INSTALLATIONM1554001900088
Required Special Tools:
: Diagnostic Tool (MUT-III Sub Assembly)
MB991824: Vehicle Communication Interface
(V.C.I.)
MB991827: MUT-III USB Cable
MB991910: MUT-III Main Harness A
INTERIOR TEMPERATURE
SENSOR REMOVAL STEPS
LOWER PANEL (REFER TO
GROUP 52A, INSTRUMENT
PA N E L P.52A-4).
1. INTERIOR TEMPERATURE
SENSOR
2. ASPIRATOR HOSEPHOTO SENSOR REMOVAL
STEPS
3. PHOTO SENSOR
Page 862 of 1500
SENSORS
HEATER, AIR CONDITIONING AND VENTILATION55-161
INSPECTIONM1554002000130.
INTERIOR TEMPERATURE SENSOR CHECK
When the resistance between the sensor terminals is mea-
sured under two or more temperature conditions, the resis-
tance should approximately satisfy the illustrated values.
NOTE:
The temperature conditions when checking should not
exceed the range shown in the diagram.
.
PHOTO SENSOR CHECK
1. Connect diagnostic tool , and check the data list of the
photo sensor. (Refer to P.55-133)
2. Check that the displayed value changes when you cover
the photo sensor with your hands.
Page 917 of 1500

GENERAL DESCRIPTION
ENGINE COOLING14-2
GENERAL DESCRIPTIONM1141000100401
The cooling system is designed to keep every
part of the engine at appropriate temperature in
whatever condition the engine may be operated.
The cooling method is of the water-cooled, pres-
sure forced circulation type in which the water
pump pressurizes coolant and circulates it
throughout the engine. If the coolant temperature exceeds the prescribed temperature, the thermo-
stat opens to circulate the coolant through the
radiator as well so that the heat absorbed by the
coolant may be radiated into the air. The water
pump is of the centrifugal type and is driven by
the drive belt from the crankshaft. The radiator is
the corrugated fin, down flow type.
SPECIAL TOOLM1141000600279
ENGINE COOLING DIAGNOSIS
INTRODUCTIONM1141005300347
The system cools the engine so that it does not over-
heat and maintains the engine at an optimum tem-
perature. The system components are the radiator,
water pump, thermostat, condenser and fan assem-
blies. Possible faults include low coolant, contamina-
tion, belt loosening and component damage.
TROUBLESHOOTING STRATEGYM1141005200340
Use these steps to plan your diagnostic strategy. If
you follow them carefully, you will be sure to find
most of the engine cooling faults.
1. Gather information from the customer.2. Verify that the condition described by the
customer exists.
3. Find and repair the malfunction by following the
SYMPTOM CHART.
4. Verify that the malfunction is eliminated. TOOL TOOL NUMBER AND
NAMESUPERSESSION APPLICATION
MB991871
LLC changerGeneral service tool Coolant refilling
Page 961 of 1500

GENERAL DESCRIPTION
INTAKE AND EXHAUST15-2
GENERAL DESCRIPTIONM1151000100446
The exhaust pipe is divided into four parts.
INTAKE AND EXHAUST DIAGNOSIS
INTRODUCTIONM1151006900321
Intake leaks usually create driveability issues that
are not obviously related to the intake system.
Exhaust leaks or abnormal noise is caused by
cracks, gaskets and fittings, or by exhaust pipe or
muffler damage due to impacts during travel. The
exhaust leaks from these sections and causes the
exhaust noise to increase. There may be cases
when the system contacts the body and vibration
noise is generated.
TROUBLESHOOTING STRATEGYM1151007000321
Use these steps to plan your diagnostic strategy. If
you follow them carefully, you will be sure that you
have exhausted most of the possible ways to find an
intake or exhaust system fault.
1. Gather information from the customer.2. Verify that the condition described by the
customer exists.
3. Find the malfunction by following the Symptom
Chart.
4. Verify malfunction is eliminated.
SYMPTOM CHARTM1151007100328
SYMPTOM PROCEDURES
INSPECTION PROCEDURE 1: Exhaust Leakage
DIAGNOSIS
STEP 1. Start the engine. Have an assistant stay
in the driver’s seat. Raise the vehicle on a hoist.
Have the assistant rev the engine while
searching for exhaust leaks.
Q: Is the exhaust leaking?
YES :
Go to Step 2.
NO : The procedure is complete.
STEP 2. Check the gasket for cracks, damage.
Q: Is the gasket damaged?
YES :
Replace the gasket, then go Step 1.
NO : Go to Step 3.
STEP 3. Check for loose coupling sections.
Q: Are there any loose each sections?
YES :
Tighten, then go to Step 1.
NO : There is no action to be taken. SYMPTOM INSPECTION PROCEDURE REFERENCE PAGE
Exhaust Leakage 1
P.15-2
Abnormal Noise 2
P.15-3