Mitsubishi Grandis. Manual - part 298

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-77

Step 14. Check the refrigerant temperature 
switch.

 Refer to 

P.55-221

.

Q: Is the refrigerant temperature switch operating 

properly?

YES : 

Go to Step 15.

NO : 

Replace the refrigerant temperature switch.

Step 15. Check the refrigerant level.

 Refer to 

P.55-193

.

Q: Is the refrigerant level correct?

YES : 

Go to Step 16.

NO : 

Correct the refrigerant level (Refer to 
On-vehicle Service 

P.55-191

.)

Step 16. Replace the A/C-ECU, and then recheck 
the trouble symptom

 Check that the compressor works normally.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the engine-ECU or the 
engine-A/T-ECU.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-78

INSPECTION PROCEDURE 8: The compressor does not work <RHD>

COMMENTS ON TROUBLE SYMPTOM

When the A/C compressor does not work, the A/C 

compressor circuit system or the CAN bus line may 
be defective.

A/C
COMPRESSOR
RELAY

A/C
COMPRESSOR
ASSEMBLY

A/C-ECU

A/C
REFRIGERANT
TEMPERATURE
SWITCH

MAGNETIC
CLUTCH

IGNITION
SWITCH (IG2)

ENGINE-ECU <M/T>
ENGINE·A/T-ECU <A/T>

RELAY
BOX

FUSIBLE
LINK

26

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 Circuit

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-79

POSSIBLE CAUSES

• Malfunction of A/C compressor

• Malfunction of A/C compressor relay

• Malfunction of A/C pressure sensor

• Damaged harness wires and connectors

• Malfunction of engine-ECU <M/T> or 

engine-A/T-ECU <A/T>

• Malfunction of the A/C-ECU

Step 1. MUT-III CAN bus diagnostics

Use the MUT-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the CAN bus lines. (Refer to GROUP 
54D 

− Troubleshooting 

P.54D-16

.)

Step 2. MUT-III diagnosis code

Check whether the air conditioner sets a diagnosis 
code or not.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Refer to diagnosis code chart 

P.55-8

.

Step 3. MUT-III data list

Check that the following service data display 
contents are normal. (Refer to 

P.55-183

.)

• Item 04: Pressure sensor

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Inspection Procedure 19: Refer to A/C 
pressure sensor system 

P.55-144

 <RHD>.

Step 4. Connector check: B-120 A/C compressor 
assembly connector and C-110 engine-ECU 
connector <M/T> or engine-A/T-ECU <A/T>

Q:  Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the connector.

Step 5. Voltage measurement at B-120 A/C 
compressor assembly connector.

(1) Disconnect the connector, and measure at the 

wiring harness side.

AC311221

Connector: B-120 <RHD>

AB

Harness side

B-120 (B)

AC310628AH

Harness side

Connector: C-110 <RHD>

C-110 (GR)

AC311221

Connector: B-120 <RHD>

AB

Harness side

B-120 (B)

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-80

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

(3) Disconnect engine-ECU connector or 

engine-A/T-ECU connector C-110 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 13.

NO : 

 Go to Step 6.

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

 Refer to GROUP 55 - On vehicle service, power 
relay 

P.55-196

.

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

YES : 

Go to Step 7.

NO : 

Replace the A/C compressor relay.

Step 7. Measure the voltage at B-16X 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 9.

NO : 

 Go to Step 8.

AC310628AH

Harness side

Connector: C-110 <RHD>

C-110 (GR)

AC309471

AC309471

Connector C-110 
(Harness side)

AF

AC310507AS

Connector B-120
(Harness side)

1

AC312170

A/C compressor relay

AC

Front of 
vehicle

Connector: B-16X

Relay box side

AC301541HX

Connector B-16X
(Relay box side)

Front of 
vehicle

1

3

2

4