Mitsubishi Montero (2002-2004). Manual - part 90

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-53

STEP 6. Using scan tool MB991502, check data list item 31: 
Air mix damper potentiometer.
Check the data list. 
Item 31: Air mix damper potentiometer 
Q: Does the data list show 100% (at MAX HOT) or 0% (at 

MAX COOL)?
YES : Go to Step 7.
NO :  Check the air mixing damper potentiometer system 

(Refer to 

P.55B-18

)

STEP 7. Check the photo sensor.
The blower speed should drop when the light-sensing section 
of the photo sensor is covered with your hand.
Q: Is the check result normal? 

YES : Go to Step 10.
NO :  Go to Step 8.

STEP 8. Check photo sensor connector D-09 and A/C-ECU 
connector D-24 for damage.
Q: Is photo sensor connector D-09 and A/C-ECU connector 

D-24 in good condition?
YES : Go to Step 9.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. The 

temperature control should work normally.

ACX01825AE

PHOTO
SENSOR

DEFROSTER
NOZLE

AC204188

CONNECTORS : D-09, D-24

D-24(B)

HARNESS SIDE

D-09

HARNESS SIDE

CG

D-24(B)

D-09

22

23

30

31

25

26

33

34

32

24

28

3635

27

29

21

1

2

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-54

STEP 9. Check the wiring harness between photo sensor 
connector D-09 (terminal 1 and 2) and A/C-ECU D-24 
(terminals 31 and 29).
Q: Is the wiring harness between photo sensor connector 

D-09 (terminal 1 and 2) and A/C-ECU D-24 (terminals 31 
and 29) in good condition?
YES : Replace the photo sensor. The temperature control 

should work normally.

NO :  Repair the wiring harness. The temperature control 

should work normally.

STEP 10. Using scan tool MB991502 check actuator test 
item 05, item 06 and item 07: air mixing damper control 
motor
Item 05, 06 and 07: air mixing damper control motor. 
Q: Is the opening angle 100% (05 activated), 50% (06 

activated) or 0% (07 activated)?
YES : Go to Step 14.
NO :  Go to Step 11.

AC204188

CONNECTORS : D-09, D-24

D-24(B)

HARNESS SIDE

D-09

HARNESS SIDE

CG

D-24(B)

D-09

22

23

30

31

25

26

33

34

32

24

28

3635

27

29

21

1

2

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-55

STEP 11. Check the air mixing damper control motor.

CAUTION

Do not apply battery voltage when the damper is in the 
MAX COOL or MAX HOT position.
Check the air mixing damper control motor by the following pro-
cedures.

Q: Does air mixing damper control motor work normally?

YES : Go to Step 12.
NO :  Replace the air mixing damper control motor and 

potentiometer. The temperature control should work 
normally.

LEVER POSITION BATTERY 

CONNECTION

LEVER 
OPERATION

At the MAX COOL 
position

• Connect 

terminal 1 to the 
positive battery 
terminal

• Connect 

terminal 2 to the 
negative battery 
terminal

The lever moves 
from the MAX 
COOL position to 
the outside position

At the MAX HOT 
position

• Connect 

terminal 2 to the 
positive battery 
terminal

• Connect 

terminal 1 to the 
negative battery 
terminal

The lever moves 
from the MAX HOT 
position to the 
inside position

ACX01456

MAX HOT
POSITION

MAX COOL
POSITION

AB

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-56

STEP 12. Check air mixing damper control motor and 
potentiometer connector D-20 and A/C-ECU connector D-
23 for damage.
Q: Is air mixing damper control motor and potentiometer 

connector D-20 and A/C-ECU connector D-23 in good 
condition?
YES : Go to Step 13.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. The 

temperature control should work normally.

STEP 13. Check the wiring harness between air mixing 
damper control motor and potentiometer connector D-20 
(terminals 2 and 1) and A/C-ECU connector D-23 (terminals 
1 and 11).
Q: Is the wiring harness between air mixing damper control 

motor and potentiometer connector D-20 (terminals 2 
and 1) and A/C-ECU connector D-23 (terminals 1 and 11) 
in good condition?
YES : Go to Step 14.
NO :  Repair the wiring harness. The temperature control 

should work normally.

AC204188

CONNECTOR : D-20, D-23

CK

7 6 5 4 3 2 1

HARNESS SIDE

D-20

D-20

D-23(B)

D-23(B)

HARNESS SIDE

1

3

4

2

12

1413

11

6

7

8

10 9

18

19

20

16

17

5

15

AC204188

CONNECTOR : D-20, D-23

CK

7 6 5 4 3 2 1

HARNESS SIDE

D-20

D-20

D-23(B)

D-23(B)

HARNESS SIDE

1

3

4

2

12

1413

11

6

7

8

10 9

18

19

20

16

17

5

15