Mitsubishi Grandis. Manual - part 313

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-137

Step 8. Check the wiring harness between D-11 
rear power transistor connector (terminal 1 and 
3) and C-104 A/C-ECU connector (terminal 60 and 
59).

NOTE: Prior to the wiring harness inspection, check 
intermediate connector C-15, and repair if necessary.

• Check the rear window defogger relay line for 

open or short circuit.

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Repair the wiring harness.

Step 9. Replace the rear power transistor and 
recheck the trouble symptom

 Check that the rear blower motor should work 
normally.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the A/C-ECU.

STEP 10. Recheck the trouble symptom

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.00-5

.)

NO : 

Replace the A/C-ECU.

AC310613

AK

Connector: C-104 <LHD>

Harness side

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

AC310631AH

Connector: C-104 <RHD>

Harness side

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

AC310207

AC

Harness side

Connector: D-11

AC310615

AD

Connector: C-15 <LHD>

AC310628AE

Connector: C-15 <RHD>

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-138

INSPECTION PROCEDURE 17: The temperature of rear air conditioner cannot be controlled <vehicles 
with dual automatic A/C>

COMMENTS ON TROUBLE SYMPTOM

If the temperature of rear air conditioner con not be 
controlled, the rear heater controller circuit system or 
the rear air mix damper control motor circuit system 
may be defective.

POSSIBLE CAUSES

• Malfunction of rear air mix damper control motor 

• Malfunction of rear heater controller

• Malfunction of the A/C-ECU

• Damaged harness wires and connectors

Step 1. 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 2.

NO : 

Refer to diagnosis code chart 

P.55-8

.

Step 2. MUT-III actuator test

Carry out the actuator test. (Refer to 

P.55-186

.)

• Item 13: R.Air mix dumper motor: 0%

• Item 14: R.Air mix dumper motor: 50%

• Item 15: R.Air mix dumper motor: 100%

Q: Does the rear blower motor work normally?

YES : 

Go to Step 3.

NO : 

Go to Step 8.

Step 3. MUT-III data list

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

P.55-183

.)

• Item 12: R.Air mix potentiometer

• Item 13: R.Air mix potentiometer (Target)

• Item 51: Rear Temperature setting

Q:  Is the check result normal?

YES : 

Go to Step 8.

NO  : 

Go to Step 4.

REAR HEATER
CONTROLLER

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-ECU

Rear heater Controller Circuit

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-139

Step 4. Connector check: E-03 rear heater 
controller connector

Q:  Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the connector.

STEP 5. Check the rear heater controller

 Refer to 

P.55-213

.

Q:  Is the check result normal?

YES : 

Go to Step 6.

NO : 

Replace the rear heater controller.

Step 6. Connector check: C-106 A/C-ECU

Q:  Is the check result normal?

YES : 

Go to Step 7.

NO : 

Repair the connector.

AC310649

AB

Connector: E-03 <LHD>             

Harness side

AC310653

AB

Connector: E-03 <RHD>             

Harness side

AC310613

AB

Connector: C-106 <LHD>

Harness side

AC310631AB

Connectors: C-106 <RHD>

Harness side

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-140

Step 7. Check the wiring harness between E-03 
rear heater controller connector (terminals 14, 
15, and 16) and C-106 A/C-ECU connector 
(terminals 15, 14 and 1).