Mitsubishi Montero (2004+). Manual - part 637

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-37

STEP 4. Check the refrigerant level.
Q: Is the refrigerant level correct?

YES : Go to Step 5.
NO :  Correct the refrigerant level (Refer to On-vehicle 

Service 

P.55A-112

). Check that the air conditioning 

works normally. 

STEP 5. Check the A/C compressor clutch relay continuity.

Follow the table below to check the A/C compressor clutch 
relay for continuity.

Q: Is the A/C compressor clutch relay in good condition?

YES : Go to Step 6.
NO :  Replace the A/C compressor clutch relay. Check that 

the air conditioning works normally. 

BATTERY VOLTAGE

TESTER 
CONNECTION 

SPECIFIED 
CONDITION

Not applied

4 

− 5

Open circuit

• Connect terminal 3 to 

the positive battery 
terminal

• Connect terminal 1 to 

the negative battery 
terminal

4 

− 5

Less than 2 
ohms

AC204715

3

1

4

5

AE

A/C 
COMPRESSOR 
CLUTCH RELAY

BATTERY

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-38

STEP 6. Measure the voltage at A/C compressor connector 
B-30.

(1) Disconnect A/C compressor connector B-30 and measure 

the voltage at the harness side.

(2) Turn the ignition switch to the "ON" position.
(3) Turn the A/C switch to the "ON" position.
(4) Turn the blower switch to the "ON" position.

(5) Measure the voltage between terminal 3 and ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Does the measured voltage correspond with this range?

YES :  Go to Step 7.
NO :   Go to Step 8.

STEP 7. Check the magnetic clutch operation.

Connect the battery (+) terminal to the air conditioning com-
pressor clutch connector terminal 3, and ground the battery (

−) 

terminal to the body of the compressor. The condition is normal 
if the sound of the magnetic clutch (click) can be heard.
Q: Can the sound of the magnetic clutch (click) be heard?

YES : Check that the air conditioning works normally. 
NO :  Replace the compressor magnet clutch. Check that 

the air conditioning works normally. 

AC204169

CONNECTOR : B-30

AE

B-30(B)

B-30(B)

2

3

1

HARNESS 
SIDE

AC204738 CY

HARNESS SIDE : B-30

2

3

1

ACX01440AB

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-39

STEP 8. Measure the voltage at A/C compressor connector 
B-30. 

(1) Disconnect A/C compressor connector B-30 and measure 

the voltage at the harness side.

(2) Disconnect powertrain control module connector D-132.

(3) Ground powertrain control module connector D-132 

(terminal 8).

(4) Turn the ignition switch to the "ON" position.

(5) Measure the voltage between terminal 3 and ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Does the measured voltage correspond with this range?

YES :  Go to Step 19.
NO :   Go to Step 9.

AC204169

CONNECTOR : B-30

AE

B-30(B)

B-30(B)

2

3

1

HARNESS 
SIDE

AC204171

CONNECTOR : D-132

D-132(GR)

D-132(GR)

AS

HARNESS SIDE

8

23

1110

24

9

6

22

7

16

17

15

3

4

1312

19

20
2726

2

1
5

14
21

25

18

AC205176

8

23

1110

24

9

6

22

7

16

17

15

3

4

13 12

19

20
27 26

2

1
5

14

21

25

18

HARNESS SIDE : D-132

AB

AC204738 CY

HARNESS SIDE : B-30

2

3

1

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-40

STEP 9. Measure the voltage at A/C compressor clutch 
relay connector A-12X.

(1) Disconnect A/C compressor connector A-12X and measure 

the voltage at the relay box side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 3 and ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Does the measured voltage correspond with this range?

YES :  Go to Step 12.
NO :   Go to Step 10.

STEP 10. Check A/C compressor clutch relay connector 
A-12X for damage.

Q:  Is A/C compressor clutch relay connector A-12X in 

good condition?
YES : Go to Step 11.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. Check 

that the air conditioning works normally.

STEP 11. Check the wiring harness between A/C 
compressor clutch relay connector A-12X (terminal 3) and 
the ignition switch (IG2).

AC204183

CONNECTOR : A-12X

AP

RELAY BOX
SIDE

2 1

5

4

3

AC204738 CV

RELAY BOX SIDE : A-12X

2 1

5

4

3

AC204183

CONNECTOR : A-12X

AP

RELAY BOX
SIDE

2 1

5

4

3

AC204183

CONNECTOR : A-12X

AP

RELAY BOX
SIDE

2 1

5

4

3