Mitsubishi Grandis. Manual - part 300

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-85

YES : 

The trouble can be an intermittent 

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

P.00-5

).

NO : 

Replace the automatic air conditioner 
control panel (A/C-ECU).

Step 4. Connector check: C-03 photo sensor 
connector and C-106 A/C-ECU connector 

Q:  Is the check result normal?

YES : 

 Go to Step 5.

NO : 

Repair the connector.

Step 5. Check the wiring harness between C-03 
photo sensor connector (terminal 1 and 2) and 
C-106 A/C-ECU connector (terminal 1 and 23).

• Check the A/C compressor relay power supply 

line for open circuit.

Q: Is the check result normal?

AC310614

AK

Connectors: C-03, C-106 <LHD>

Harness side

C-106

C-03

C-106

Harness side

C-03

AC310632 AF

Connectors: C-03, C-106 <RHD>

Harness side

C-106

C-03

C-106

Harness side

C-03

AC310614

AK

Connectors: C-03, C-106 <LHD>

Harness side

C-106

C-03

C-106

Harness side

C-03

AC310632 AF

Connectors: C-03, C-106 <RHD>

Harness side

C-106

C-03

C-106

Harness side

C-03

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-86

YES : 

 Go to Step 6.

NO : 

Repair the wiring harness. Check that the 
air conditioner works normally.

Step 6. Replace the photo sensor and recheck 
the trouble symptom

 Check that the air conditioner works normally.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the automatic air conditioner 
control panel (A/C-ECU).

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-87

INSPECTION PROCEDURE 10: The PTC heater does not work <LHD>

COMMENTS ON TROUBLE SYMPTOM

When the PTC heater does not work under the 
following conditions, the PTC heater switch system 
or the PTC heater circuit system may be defective.

PTC heater operating conditions

• PTC heater switch: ON

• Air outlet: FOOT/DEF, FOOT, FACE/FOOT

• Temperature control dial: MAX HOT

• Coolant temperature: 82 degrees celsius or less

FUSIBLE
LINK

28

IGNITION
SWITCH (IG2)

PTC
HEATER
RELAY 2

PTC
HEATER
RELAY 1

PTC
HEATER

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

PTC Heater Relay Circuit

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-88

NOTE: When the coolant temperature becomes 
above 82 degrees celsius and PTC heater stops the 
operation, the PTC heater does not operate until 
coolant temperature becomes below 72 degrees 
celsius.

POSSIBLE CAUSES

• Malfunction of the PTC heater switch system

• Damaged the wiring harness or connectors

• Malfunction of the PTC heater relay 1

• Malfunction of the PTC heater relay 2

• Malfunction of the PTC heater

• Malfunction of the automatic air conditioner 

control panel (A/C-ECU)

DIAGNOSIS

Step 1. MUT-III data list

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

P.55-183

.)

• Item 35: PTC heater switch

Q: Does the blower motor work normally? 

YES : 

Go to Step 4.

NO : 

Go to Step 2.

Step 2. Connector check: C-106 A/C-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Repair the connector.

Step 3. Voltage measurement at C-106 A/C-ECU 
connector.

(1) Disconnect the connector, and measure at the 

wiring harness side.

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

(4) Voltage between terminal 26 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 28.

NO : 

Inspection Procedure 24: Refer to PTC 
heater switch system <LHD>

P.55-168

  .

Step 4. Connector check: C-103 PTC heater 
connector

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the connector.

AC310613

AB

Connector: C-106 <LHD>

Harness side

AC310613

AB

Connector: C-106 <LHD>

Harness side

AC310507

Connector C-106 
(Harness side)

AT

AC310613

AF

Connector: C-103 <LHD>

Harness side