Mitsubishi Outlander (2003+). Manual - part 554

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-31

INSPECTION PROCEDURE 2: The air conditioner does not work at all. <4G63>

CIRCUIT OPERATION
If cool air is not distributed when the A/C switch is on, 
A/C compressor relay system may be defective. 

Possible causes

•

Improper amount of refrigerant

•

Malfunction of the A/C pressure sensor

•

Malfunction of the A/C compressor relay

•

Malfunction of the magnetic clutch

•

Malfunction of the A/C refrigerant temperature 
switch

•

Damaged the wiring harness or connectors

•

Malfunction of the automatic air conditioner 
control panel (A/C-ECU)

20

10

14

4

(MU801585)

11

1

13

12

2 3

17

7

1516

5 6

1819

8 9

Wire colour code
B : Black     LG : Light green     G : Green     L : Blue     W : White     Y : Yellow     SB : Sky blue
BR : Brown     O : Orange     GR : Gray     R : Red     P : Pink     V : Violet   

A/C 
COMPRESSOR 
RELAY

A/C
COMPRESSOR
ASSEMBLY

A/C
REFRIGERANT
TEMPERATURE
SWITCH

MAGNETIC
CLUTCH

A/C-ECU

A/C PRESSURE
SENSOR

IGNITION 
SWITCH (IG2)

ENGINE-ECU

BATTERY

RELAY 
BOX

A/C Compressor Circuit

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-32

DIAGNOSIS

Step 1. Use the MUT-II/III to confirm a diagnosis 
code.

On completion, check that the diagnosis code is not 
reset.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Refer to diagnosis code chart 

P.55B-4

.

Step 2. Check the blower operation.
(1) Turn the ignition switch to the ON position.
(2) Blower knob: Other than OFF
(3) Check that the air comes out of the blower.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Refer to Inspection Procedure 4 "The 
blower does not work."

STEP 3. Check the defogger and outside/inside 
air selection damper control motor operation.

Q: Do the defogger and outside/inside air selection 

damper control motor work normally?

YES : 

Go to Step 4.

NO : 

Refer to Inspection procedure 10 
"Malfunction of the A/C-ECU power supply 
system 

P.55B-88

."

STEP 4. Check the A/C compressor.

Check the A/C compressor for compressor oil leaks.

Q: Is the check result satisfactory?

YES : 

Go to Step 5.

NO : 

Replace the A/C compressor or the 
expansion valve.

STEP 5. Measure the voltage at B-27 A/C 
compressor connector.

(1) Disconnect the connector, and measure at the 

wiring harness side.

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

(3) Disconnect engine-ECU connector C-134 and 

earth terminal 8.

(4) Voltage between terminal 1 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 17.

NO : 

 Go to Step 6.

STEP 6. Check the A/C compressor relay 
continuity.

 Refer to GROUP 55A - On vehicle service, power 
relay 

P.55A-57

.

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

YES : 

Go to Step 7.

NO : 

Replace the A/C compressor relay.

AC301648

Connector: B-27

Harness side

1

B-27(B)

AB

AC301397

Connector: C-134

AO

Harness side

22

9

14

15

2 1

3

16

1918

5 4

17

6

21

7

20

8

25

12

10

23

11

24

26

13

JAE-E

AC301541BU

Connector B-27
(Harness side)

1

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-33

STEP 7. Measure the voltage at B-18X A/C 
compressor relay connector.

(1) Remove the relay, and measure at the relay block 

side.

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

(3) Voltage between terminal 3 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 10.

NO : 

 Go to Step 8.

STEP 8. Connector check: B-18X A/C 
compressor relay connector.

Q:  Is the check result normal?

YES : 

Go to Step 9.

NO : 

Repair the connector.

STEP 9. Check the wiring harness between B-18X 
A/C compressor relay connector terminal No.3 
and the ignition switch (IG2).

AC301483AG

Front of 
vehicle

Relay box side

1

3

2

4

B-18X

-

Connector: B-18X

AC301541BV

Connector B-18X
(Relay box side)

Front of 
vehicle

1

3

2

4

AC301483AG

Front of 
vehicle

Relay box side

1

3

2

4

B-18X

-

Connector: B-18X

AC301483AG

Front of 
vehicle

Relay box side

1

3

2

4

B-18X

-

Connector: B-18X

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-34

NOTE: 

Prior to the wiring harness inspection, check junction 
block connectors C-203, C-202 and intermediate 
connector C-106, and repair if necessary.

•

Check the A/C compressor relay power supply 
line for open circuit.

Q: Is the check result normal?

YES : 

The trouble can be an intermittent 

malfunction (Refer to GROUP 00, How to 
Cope with Intermittent Malfunction 

P.00-6

).

NO : 

Repair the wiring harness.

STEP 10. Measure the voltage at B-18X A/C 
compressor relay connector.

(1) Remove the relay, and measure at the relay block 

side.

(2) Voltage between terminal 4 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 13.

NO : 

 Go to Step 11.

AC301397

Connector: C-106

AG

C-106(GR)

13

3

7

16

19

15

14

18

17

12

6

4

8

1

9

11

10

5

2

AC210475

Connectors: C-202, C-203

AG

Junction block (Front view)

C-202

C-203

Harness side

C-203

C-202

4

6 5

3

2

1

10

1

6

14

5

12

13

4

11

7

2

3

8

9

AC301483AG

Front of 
vehicle

Relay box side

1

3

2

4

B-18X

-

Connector: B-18X

AC301541BW

Connector B-18X
(Relay box side)

Front of 
vehicle

1

3

2

4