Mitsubishi Grandis. Manual - part 309

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-121

COMMENTS ON TROUBLE SYMPTOM

If the rear blower motor does not operate, the rear 
blower motor circuit system may be defective.

POSSIBLE CAUSES

• Malfunction of rear blower relay

• Malfunction of rear blower motor

• Malfunction of rear power transistor 

• Malfunction of the A/C-ECU

• Damaged harness wires and connectors

DIAGNOSIS

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

.

REAR
HEATER
CONTROLLER

A/C-ECU

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

Rear Heater Controller Circuit <R.H.D>

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-122

Step 2. MUT-III actuator test

Carry out the actuator test. (Refer to 

P.55-186

.)

• Item 04: Rear blower fan: OFF

• Item 05: Rear blower fan: AUTO <vehicles with 

dual automatic A/C>

• Item 06: Rear blower fan: Lo

• Item 07: Rear blower fan: Middle

• Item 08: Rear blower fan: High

Q: Does the rear blower motor work normally?

YES : 

Go to Step 3.

NO : 

Go to Step 9.

Step 3. MUT-III data list

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

P.55-183

.)

• Item 22: Rear blower fan

• Item 23: Rear blower fan (Target)

• Item 31: Rear fan SW (Front)

• Item 32: Rear control OFF switch

• Item 33: Rear control fan OFF switch

Q:  Is the check result normal?

YES : 

Go to Step 8.

NO <Item 22, 23, 32, 33 is abnormal> : 

Go to Step 

4.

NO <Item 31 is abnormal> : 

Refer to Inspection 

Procedure 20: rear fan switch system 
<LHD>

P.55-146

  or Inspection Procedure 

21: rear fan switch system <RHD>

P.55-149

 

.

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.

AC310649

AB

Connector: E-03 <LHD>             

Harness side

AC310653

AB

Connector: E-03 <RHD>             

Harness side

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-123

Step 6. Connector check: C-104 A/C-ECU

Q:  Is the check result normal?

YES : 

Go to Step 7.

NO : 

Repair the connector.

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

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-124

Step 7. Check the wiring harness between E-03 
rear heater controller connector (terminals 4, 6, 
7, 8 and 9) and C-104 A/C-ECU connector 
(terminals 70, 68, 67, 66 and 65).