Mitsubishi 380. Manual - part 196

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-80

STEP 9. Measure the voltage at A/C compressor clutch 
relay connector B-18X. 

CAUTION

The top and bottom of the A/C compressor connector are 
difficult to identify. Prior to inspection, confirm the triangle 
mark on the relay box.
(1) Disconnect A/C compressor connector B-18X and measure 

the voltage at the relay box side.

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

(3) Measure the voltage between terminal 2 and ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Is the measured voltage approx. 12 volts?

YES :  Go to Step 11.
NO :   Go to Step 10.

STEP 10. Check the wiring harness between A/C 
compressor clutch relay connector B-18X (terminal 2) and 
the ignition switch (IG2).

AC305977AJ

CONNECTOR: B-18X

RELAY BOX SIDE

FRONT OF 
VEHICLE

JUNCTION BLOCK 

TRIANGLE MARK

AC209365GT

CONNECTOR B-18X 
(RELAY BOX SIDE)

AC305977AJ

CONNECTOR: B-18X

RELAY BOX SIDE

FRONT OF 
VEHICLE

JUNCTION BLOCK 

TRIANGLE MARK

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-81

NOTE: Also check intermediate connector A-13, junction block 
connectors C-214 and C-215 for loose, corroded, or damaged 
terminals, or terminals pushed back in the connector. If inter-
mediate connector A-13, junction block connector C-214 or 
C-215 is damaged, repair or replace the connector as 
described in GROUP 00E, Harness Connector Inspection 

P.00E-2

.

Q: Is the wiring harness between A/C compressor clutch 

relay connector B-18X (terminal 2) and the ignition 
switch (IG2) in good condition?
YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunctions 

P.00-14

.

NO :  Repair the wiring harness. Check that the air 

conditioning works normally.

AC305210

A-13 (GR)

AR

CONNECTOR: A-13

25DB103A

CONNECTORS: C-214, C-215

JUNCTION BLOCK 

(FRONT VIEW)

C-215

HARNESS SIDE

C-214

C-214

HARNESS SIDE

C-215

10

1

6

14

5

12

13

4

11

7

2

3

8

9

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-82

STEP 11. Measure the voltage at A/C compressor clutch 
relay connector B-18X. 

CAUTION

The top and bottom of the A/C compressor connector are 
difficult to identify. Prior to inspection, confirm the triangle 
mark on the relay box.
(1) Disconnect A/C compressor connector B-18X and measure 

the voltage at the wiring harness side.

(2) Measure the voltage between terminal 1 and ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Is the measured voltage approx. 12 volts?

YES :  Go to Step 13.
NO :   Go to Step 12.

STEP 12. Check the wiring harness between A/C 
compressor clutch relay connector B-18X (terminal 1) and 
the battery.

AC305977AJ

CONNECTOR: B-18X

RELAY BOX SIDE

FRONT OF 
VEHICLE

JUNCTION BLOCK 

TRIANGLE MARK

AC209365GU

CONNECTOR B-18X 
(RELAY BOX SIDE)

AC305977AJ

CONNECTOR: B-18X

RELAY BOX SIDE

FRONT OF 
VEHICLE

JUNCTION BLOCK 

TRIANGLE MARK

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-83

NOTE: Also check intermediate connector A-13 for loose, cor-
roded, or damaged terminals, or terminals pushed back in the 
connector. If intermediate connector A-13 is damaged, repair or 
replace the connector as described in GROUP 00E, Harness 
Connector Inspection 

P.00E-2

.

Q: Is the wiring harness between A/C compressor clutch 

relay connector B-18X (terminal 1) and the battery in 
good condition?
YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunctions 

P.00-14

.

NO :  Repair the wiring harness. Check that the air 

conditioning works normally.

STEP 13. Check the wiring harness between A/C 
compressor clutch relay connector B-18X (terminal 4) and 
A/C compressor assembly connector B-28 (terminal 1).
Q: Is the wiring harness between A/C compressor clutch 

relay connector B-18X (terminal 4) and A/C compressor 
connector B-28 (terminal 1) in good condition?
YES : Go to Step 14.
NO :  Repair the wiring harness. Check that the air 

conditioning works normally.

AC305210

A-13 (GR)

AR

CONNECTOR: A-13

AC305977AJ

CONNECTOR: B-18X

RELAY BOX SIDE

FRONT OF 
VEHICLE

JUNCTION BLOCK 

TRIANGLE MARK

AC305218

B-28 (B)

HARNESS SIDE

AB

CONNECTOR: B-28 <3.8 L>