Page 714 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-13
STEP 4. Check A/C-ECU connector C-15, C-16 and interior
temperature sensor connector C-123 for loose, corroded
or damaged terminals, or terminals pushed back in the
connector.
Q: Are A/C-ECU connectors C-15, C-16 and interior
temperature sensor connector C-123 in good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Refer to GROUP
00E, Harness Connector Inspection P.00E-2. Then go
to Step 7.
Page 715 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-14
STEP 5. Check the wiring harness between A/C-ECU
connector C-15 (terminals 20), C-16 (terminals 22) and
interior temperature sensor connector C-123 (terminals 1
and 2).
Q: Are the wiring harnesses between A/C-ECU connector
C-15 (terminals 20), C-16 (terminals 22) and interior
temperature sensor connector C-123 (terminals 1 and 2)
in good condition?
YES : Go to Step 6.
NO : Repair the wiring harness. Then go to Step 7.
Page 716 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-15
STEP 6. Check the interior temperature sensor.
(1) Disconnect interior temperature sensor connector C-123.
(2) When the resistance between the sensor terminals is
measured under two or more temperature conditions, the
resistance should approximately satisfy the illustrated
values.
NOTE: The temperature conditions when checking should
not exceed the range shown in the diagram.
Q: Is the interior temperature sensor in good condition?
YES : Replace the A/C-ECU. Then go to Step 7.
NO : Replace the interior temperature sensor. Then go to
St e p 7 .
STEP 7. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect diagnostic tool to the data link connector
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
YES : The procedure is complete.
NO : Return to Step 1.
Page 834 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-133
DATA LIST REFERENCE TABLEM1554005100136
MUT-III
DIAGNOSTIC
TOOL DISPLAYITEM
NO.INSPECTION ITEM INSPECTION REQUIREMENT NORMAL VALUE
Inside
temperature
sensor59 Interior temperature
sensorIgnition switch: ON Inside air
temperature and
temperature
displayed on the
diagnostic tool are
identical.
Outside
temperature
sensor58 Outside temperature
sensorIgnition switch: ON Outside air
temperature and
temperature
displayed on the
diagnostic tool are
identical.
Air thermo sensor 20 Air thermo sensor Ignition switch: ON The temperature
measured behind
the evaporator
matches the
displayed value on
the diagnostic tool
while the engine is
cold.
Pressure sensor 61 A/C pressure sensor Ignition switch: ON Measured refrigerant
pressure is nearly
equal to the value
shown on the
diagnostic tool
(MPa).
Water
temperature
sensor62 Engine coolant
temperature sensor
(Data received by
CAN
Communication)Ignition switch: ON Engine coolant
temperature and
temperature
displayed on the
diagnostic tool are
identical.
Photo sensor 67 Photo sensor Ignition switch: ON Amount of light is
proportional to
voltage displayed on
the diagnostic tool.
Air mix
potentiometer63 Air mixing damper
control motor
potentiometerIgnition switch: ON Damper
positionOpening degree (V)
MAX. HOT Approx. 5
MAX. COOL Approx. 0
Air mix
potentiometer
(Target)64 Target value for air
mixing damper
control motor
potentiometerIgnition switch: ON Damper
positionOpening degree (V)
MAX. HOT Approx. 5
MAX. COOL Approx. 0
Page 839 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-138
16 Potentiometer power supply Ignition switch: ON 5 V
17 Power transistor (BASE) When the blower speed
selection dial shows Maximum
air volume.1 V
18 Power transistor
(COLLECTOR)When the blower speed
selection dial shows Maximum
air volume.12.1 V
19 Photo sensor Ignition switch: ON 5 V
20 Sensors and potentiometers
groundAlways 0 V
21 Mode selection damper control
motor potentiometer inputWhen the damper is moved to
the FACE position. 4 V
22 Interior temperature sensor Ignition switch: ON 5 V
23 Ambient temperature sensor
inputWhen sensor temperature is
25
C (77F) [4 k]1.9 V
24 Air thermo sensor input When sensor temperature is
25
C (77F) [1.5 k]2.2 V
25 Photo sensor ground Ignition switch: ON 0 V
26 A/C pressure sensor at 2.6 MPa 3.9 V
27 Ground Always 0 V
28 Power supply to the ignition
switch (IG2)Ignition switch: ON Battery positive voltage
29 Air mixing damper control motor
potentiometer inputWhen the damper door is
moved to the MAX. HOT
position.1.4 V
30 Illumination ground Always 0 V
31 ILL power supply Lighting switch: ON Battery positive voltage
34 A/C pressure sensor ground Always 0 V
36 Power supply to the ignition
switch (ACC)Ignition switch: ON Battery positive voltage TERMINAL
NO.CHECK ITEM CHECKING REQUIREMENTS NORMAL CONDITION
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 887 of 1500
INSPECTION TERMINAL
COMPONENT LOCATIONS70-8
INSPECTION TERMINALM1701000200354
SENSORM1701000600415
NAME SYMBOL NAME SYMBOL
A/C pressure sensor I Interior temperature sensor
A/C>S
A/T control solenoid valve assembly
(Incorporating transmission fluid
temperature sensor)N Knock sensor C
Accelerator pedal position sensor R Left bank heated oxygen sensor (front)
<3.8L Engine>P
Air thermo sensor T Left bank heated oxygen sensor (rear)
<3.8L Engine>P
Ambient temperature sensor L Manifold absolute pressure sensor B
Camshaft position sensor D Mass airflow sensor G
Crankshaft position sensor A Sunroof assembly (Incorporating pulse
sensor)U
Fuel pump module (Incorporating fuel
level sensor (main) and fuel tank
temperature sensor)W Output shaft speed sensor H
Fuel level sensor (sub) V Photo sensor Q
Right bank heated oxygen sensor
(front) <3.8L Engine>O
Input shaft speed sensor K Right bank heated oxygen sensor (rear)
<3.8L Engine>O