Mitsubishi Montero (2002-2004). Manual — part 89

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-49

STEP 26. Check A/C-ECU connector D-23 and heater
blower controller unit connector D-17 for damage.
Q: Are A/C-ECU connector D-23 and heater blower

controller unit connector D-17 in good condition?
YES : Go to Step 27.
NO : Repair or replace the connector. Refer to GROUP

00E, Harness Connector Inspection

P.00E-2

. Check

that the air conditioning works normally.

STEP 27. Check the wiring harness between A/C-ECU
connector D-23 (terminal 10) and heater blower controller
unit connector D-17 (terminal 3).
Q: Is the wiring harness between A/C-ECU connector D-23

(terminal 10) and heater blower controller unit
connector D-17 (terminal 3) in good condition?
YES : Go to Step 28.
NO : Repair the wiring harness. Check that the air

conditioning works normally.

AC204171

CONNECTOR : D-17

AP

1

2

3

4

HARNESS
SIDE

AC204170

CONNECTOR : D-23

D-23(B)

D-23(B)

CP

HARNESS
SIDE

1

3

4

2

12

1413

11

6

7

8

10 9

18

19

20

16

17

5

15

AC204171

CONNECTOR : D-17

AP

1

2

3

4

HARNESS
SIDE

AC204170

CONNECTOR : D-23

D-23(B)

D-23(B)

CP

HARNESS
SIDE

1

3

4

2

12

1413

11

6

7

8

10 9

18

19

20

16

17

5

15

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-50

STEP 28. Check the flexible flat cable (FFC).
(1) The FCC is connected to the automatic air conditioning

control panel assembly. Check that the FCC connection is
contaminated with foreign material or loose. (Refer to

P.55B-136

.)

(2) There should be continuity across the FFC terminals.
Q: Is the FFC normal?

YES : Go to Step 29.
NO : Repair the FFC (Refer to

P.55B-136

). The

temperature control should work normally.

STEP 29. Check the A/C switch.
There should be continuity between terminals 10 and 13 while
the A/C switch is pushed.
Q: Is the check result normal?

YES : Replace the A/C-ECU. (Refer to

P.55B-136

.) Then go

to Step 30.

NO : Replace the automatic air-conditioning control panel.

Check that the air conditioning works normally.

STEP 30. Retest the system.
Q: Do the air conditioning work normally?

YES : No action is necessary and testing is complete.
NO : Replace the powertrain control module. Check that

the air conditioning works normally.

AC205264AB

AC205403

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

AF

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-51

INSPECTION PROCEDURE 3: A/C Outlet Air Temperature cannot be Set.

.

TECHNICAL DESCRIPTION (COMMENT)
If the A/C outlet air temperature can not be adjusted,
the air mixing damper control motor system may be
defective.

.

Photo Sensor and Air Mix Damper Motor Circuit

AC204170 DZ

D-23(B)

D-24(B)

D-20

D-09

CONNECTORS : D-09, D-20, D-23, D-24

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-52

TROUBLESHOOTING HINTS

• Malformation of the photo sensor

• Malformation of the air mixing damper control

motor and potentiometer

• Malformation of the A/C-ECU

• Malformation of the flexible flat cable

DIAGNOSIS

STEP 1. Using scan tool MB991502, read the Diagnostic
trouble code.
Q: Is a diagnostic trouble code set?

YES : Refer to

P.55B-5

.

NO : Go to Step 2.

STEP 2. Using scan tool MB991502, check data list item 11:
Inside air temperature sensor.
Check the data list.
Item 11: Inside air temperature sensor
Q: Are the inside air temperature and indicated

temperature on scan tool MB991502 almost equal?
YES : Go to Step 3.
NO : Replace the A/C-ECU. (Refer to

P.55B-136

.) The

temperature control should work normally.

STEP 3. Using scan tool MB991502, check data list item 13:
Outside air temperature sensor.
Check the data list.
Item 13: Outside air temperature sensor
Q: Are the outside air temperature and indicated

temperature on scan tool MB991502 almost equal?
YES : Go to Step 4.
NO : Check the outside air temperature sensor system

(Refer to

P.55B-8

).

STEP 4. Using scan tool MB991502, check data list item 15:
Heater water temperature sensor.
Check the data list.
Item 15: Heater water temperature sensor
Q: Are the heater core surface temperature and indicated

temperature on scan tool MB991502 almost equal?
YES : Go to Step 5.
NO : Check the heater water temperature sensor system

(Refer to

P.55B-12

).

STEP 5. Using scan tool MB991502, check data list item 21:
Air thermo sensor.
Check the data list.
Item 21: Air thermo sensor
Q: Are the evaporator blowout temperature and indicated

temperature on scan tool MB991502 almost equal?
YES : Go to Step 6.
NO : Check the outside air temperature sensor system

(Refer to

P.55B-8

).