Mitsubishi Galant (2004+). Manual - part 777

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-247

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TECHNICAL DESCRIPTION (COMMENT)
The A/C-ECU power system may be defective if the 
air conditioner, defogger, and outside/inside air 
selection damper motor all do not operate normally.

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TROUBLESHOOTING HINTS

• Malfunction of the A/C-ECU

• Damaged harness wires or connectors

DIAGNOSIS

Required Special Tool:

• MB991223: Test Harness Set

STEP 1. Check A/C-ECU connector C-16 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.

Q:  Is A/C-ECU connector C-16 in good condition?

YES : Go to Step 2.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. Check 

that the air conditioning works normally.

AC305415

CONNECTORS: C-211, C-215

JUNCTION BLOCK 
(FRONT VIEW)

C-215

C-211

BA

AC305233

HARNESS SIDE

C-16 (B)

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36

BX

CONNECTOR: C-16

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-248

STEP 2. Measure the voltage at A/C-ECU connector C-16. 

(1) Disconnect A/C-ECU connector C-16 and measure the 

voltage at the harness side.

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

(3) Measure the voltage between terminal 28 and ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Is the measured voltage approx. 12 volts?

YES :  Go to Step 4.
NO :   Go to Step 3.

STEP 3. Check the wiring harness between A/C-ECU 
connector C-16 (terminal 28) and the ignition switch (IG2).

AC305233

HARNESS SIDE

C-16 (B)

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36

BX

CONNECTOR: C-16

AC209365

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36

CONNECTOR C-16 
(HARNESS SIDE)

HK

AC305233

HARNESS SIDE

C-16 (B)

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36

BX

CONNECTOR: C-16

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-249

NOTE: Also check joint connector C-03, junction block connec-
tors C-211 and C-215 for loose, corroded, or damaged termi-
nals, or terminals pushed back in the connector. If joint 
connector C-03, junction block connector C-211 or C-215 is 
damaged, repair or replace the connector as described in 
GROUP 00E, Harness Connector Inspection 

P.00E-2

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Q: Is the wiring harness between A/C-ECU connector C-16 

(terminal 28) and the ignition switch (IG2) 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

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NO :  Repair the wiring harness. Check that the air 

conditioning works normally.

AC305231BP

CONNECTOR: C-03

AC305416

CONNECTORS: C-211, C-215

JUNCTION BLOCK 
(FRONT VIEW)

C-215

C-211

HARNESS SIDE

C-211

HARNESS SIDE

C-215

AK

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-250

STEP 4. Measure the voltage at A/C-ECU connector C-16. 

(1) Disconnect A/C-ECU connector C-16 and measure the 

voltage at the harness side.

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

(3) Measure the voltage between terminal 36 and ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Is the measured voltage approx. 12 volts?

YES :  Go to Step 6.
NO :   Go to Step 5.

STEP 5. Check the wiring harness between A/C-ECU 
connector C-16 (terminal 36) and the ignition switch (ACC).

AC305233

HARNESS SIDE

C-16 (B)

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36

BX

CONNECTOR: C-16

AC209365

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36

CONNECTOR C-16 
(HARNESS SIDE)

HL

AC305233

HARNESS SIDE

C-16 (B)

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BX

CONNECTOR: C-16