Mitsubishi Galant (2004+). Manual - part 760

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-179

STEP 7. Check the wiring harness between A/C-ECU 
connector C-10 (terminal 8) and the battery.

NOTE: Also check joint connector C-01 and intermediate con-
nector C-29 for loose, corroded, or damaged terminals, or ter-
minals pushed back in the connector. If joint connector C-01 or 
intermediate connector C-29 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-ECU connector C-10 

(terminal 8) 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 

P.00-6

.

NO :  Repair the wiring harness. Check that the air 

conditioning works normally.

AC305233AW

CONNECTOR: C-10

HARNESS SIDE

C-10 (B)

AC305232

CONNECTORS: C-01, C-29

C-01

C-29

AS

C-01

C-29

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-180

STEP 8. Measure the resistance at A/C-ECU connector 
C-10.

(1) Disconnect A/C-ECU connector C-10, and measure at the 

wiring harness side.

(2) Measure the resistance between terminal 2 and ground.

• The measured value should be 2 ohms or less.

Q: Does the measured resistance value correspond with 

this range?
YES : Replace the A/C-ECU, and check that the air 

conditioning works normally.

NO :   Go to Step 9.

STEP 9. Check the wiring harness between A/C-ECU 
connector C-10 (terminal 2) and the ground.

Q: Is the wiring harness between A/C-ECU connector C-10 

(terminal 2) and ground in good condition?
YES : It can be assumed that this malfunction is intermittent. 

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

P.00-6

.

NO :  Repair the wiring harness. Check that the air 

conditioning works normally.

AC305233AW

CONNECTOR: C-10

HARNESS SIDE

C-10 (B)

AC209364

CONNECTOR C-10 
(HARNESS SIDE)

IU

AC305233AW

CONNECTOR: C-10

HARNESS SIDE

C-10 (B)

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-181

SYMPTOM CHART <MIDDLE TYPE>

M1552009900495

CAUTION

During diagnosis, a DTC code associated with 
other system may be set when the ignition switch 
is turned on with connector(s) disconnected. On 
completion, confirm all systems for DTC code(s). 
If DTC code(s) are set, erase them all.

SYMPTOM

INSPECTION 
PROCEDURE

REFERENCE 
PAGE

When the ignition switch is "ON", the A/C does not operate.

1.

P.55A-182

When the air outlet changeover control knob is moved to DEFROSTER or 
DEFROSTER/FOOT position, the A/C or the inside/outside air 
changeover damper motor does not operate.

2.

P.55A-183

Outside/Inside air changeover is not possible.

3.

P.55A-184

When the A/C is operating, temperature inside the passenger 
compartment does not decrease (cool air is not emitted).

4.

P.55A-190

Blower fan and motor do not turn.

5.

P.55A-208

Blower air amount cannot be changed.

6.

P.55A-220

The A/C indicator flashes.

7.

P.55A-225

Defogger function does not operate.

8.

P.55A-233

Defogger timer function does not operate.

9.

P.55A-245

Malfunction of the A/C-ECU power supply system.

10.

P.55A-246

Condenser fan does not operate.

11.

REFER TO 
GROUP 14 

− 

SYMPTOM 
CHART 

P.14-3

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-182

SYMPTOM PROCEDURES <MIDDLE TYPE>

INSPECTION PROCEDURE 1: When the Ignition Switch is "ON", the A/C does not Operate.

.

TECHNICAL DESCRIPTION (COMMENT)
The blower system or the compressor system may 
be defective if there is no cool air coming from the 
vents.

.

TROUBLESHOOTING HINTS

• Malfunction of blower motor

• Malfunction of A/C compressor

DIAGNOSIS

Check that the blower motor operation when the blower 
switch is moved to the "HI" position.
(1) Turn the ignition switch to the "ON" position.
(2) Turn the blower speed selection dial to the blower operating 

position.

Q: Does the blower motor operate when the speed 

selection dial is turned to the blower operating 
position?
YES : Refer to Inspection procedure 4 "When the A/C is 

operating, temperature inside the passenger 
compartment does not decrease (cool air not emitted) 

P.55A-190

."

NO :  Refer to Inspection procedure 5 "Blower fan and 

motor do not turn 

P.55A-208

."