Mitsubishi Galant 9G. Manual - part 293

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-248

STEP 7. Check the wiring harness between A/C-ECU 
connector C-16 (terminal 3) 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-16 

(terminal 3) 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 

− How to 

Cope with Intermittent Malfunctions 

P.00-14

.

NO :  Repair the wiring harness. Check that the air 

conditioning works normally.

AC305233

CONNECTOR: C-15

BG

C-105 (B)

HARNESS SIDE

AC305232

CONNECTORS: C-01, C-29

C-01

C-29

AS

C-01

C-29

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-249

STEP 8. Measure the resistance at A/C-ECU connector 
C-16.
(1) Disconnect A/C-ECU connector C-16, and measure at the 

wiring harness side.

(2) Measure the resistance between terminal 27 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-16 (terminal 27) and the ground.
Q: Is the wiring harness between A/C-ECU connector C-16 

(terminal 27) 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 

− How to 

Cope with Intermittent Malfunctions 

P.00-14

. check 

that the air conditioning works normally.

NO :  Repair the wiring harness. Check that the air 

conditioning works normally.

AC305233

HARNESS SIDE

C-16 (B)

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

BX

CONNECTOR: C-16

AC209364

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

CONNECTOR C-16 
(HARNESS SIDE)

JE

AC305233

HARNESS SIDE

C-16 (B)

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

BX

CONNECTOR: C-16

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-250

DATA LIST REFERENCE TABLE

M1554005100136

MUT-III SCAN 
TOOL DISPLAY

ITEM 
NO.

INSPECTION ITEM INSPECTION REQUIREMENT

NORMAL VALUE

Ambient air 
temperature 
sensor

02

Ambient air 
temperature sensor

Ignition switch: ON

Outside air 
temperature and 
temperature 
displayed on the 
scan tool are 
identical.

Air thermo sensor 03

Air thermo sensor

Ignition switch: ON

The temperature 
measured behind 
the evaporator 
matches the 
displayed value on 
the scan tool while 
the engine is cold.

Pressure sensor 04

A/C pressure sensor Ignition switch: ON

Measured refrigerant 
pressure is nearly 
equal to the value 
shown on the scan 
tool.

Heater water 
temperature 
sensor

05

Engine coolant 
temperature sensor 
(Data received by 
CAN 
Communication)

Ignition switch: ON

Engine coolant 
temperature and 
temperature 
displayed on the 
scan tool are 
identical.

Air mix 
potentiometer

10

Air mixing damper 
control motor 
potentiometer

Ignition switch: ON Damper 

position

Opening degree (%)

MAX. HOT

Approx. 100

MAX. COOL

Approx. 0

Air mix 
potentiometer 
(Target)

11

Target value for air 
mixing damper 
control motor 
potentiometer

Ignition switch: ON Damper 

position

Opening degree (%)

MAX. HOT

Approx. 100

MAX. COOL

Approx. 0

Air outlet c/o 
potentiometer

12

Mode selection 
damper control 
motor potentiometer

Ignition switch: ON Damper 

position

Opening degree (%)

FACE

Approx. 100

FOOT

Approx. 75

FOOT/DEF.

Approx. 50

DEF.

Approx. 0

Air outlet c/o 
potentiometer 
(target)

13

Target value for 
mode selection 
damper control 
motor potentiometer

Ignition switch: ON Damper 

position

Opening degree (%)

FACE

Approx. 100

FOOT

Approx. 75

FOOT/DEF.

Approx. 50

DEF.

Approx. 0

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-251

In/out air 
changeover 
damper motor

15

Outside/inside air 
selection damper 
control motor

Ignition switch: ON Damper set 

position

Damper position

Fresh air 
position

FRESH

Air recirculation 
position

RECIRC

Blower fan

20

Blower motor

Ignition switch: ON

The actual air 
volume (blower 
motor speed) 
corresponds to the 
air volume shown on 
the scan tool.

Blower fan 
(Target)

21

Target value for 
blower motor

Ignition switch: ON

The air volume set 
by the heater control 
corresponds to the 
value shown on the 
scan tool.

Air conditioning 
switch

30

Air conditioning 
switch

Ignition switch: ON Air conditioning 

switch: ON

Scan tool indication: 
ON

Air conditioning 
switch: OFF

Scan tool indication: 
OFF

Rear defogger 
switch

34

Rear window 
defogger switch

Ignition switch: ON Rear window 

defogger 
switch: ON

Scan tool indication: 
ON

Rear window 
defogger 
switch: OFF

Scan tool indication: 
OFF

Low pressure 
judgment

40

Refrigerant pressure Ignition switch: ON

The scan tool 
indication is normal

Refrigerant leak

41

Refrigerant leak

Ignition switch: ON

The scan tool 
indication is normal

MUT-III SCAN 
TOOL DISPLAY

ITEM 
NO.

INSPECTION ITEM INSPECTION REQUIREMENT

NORMAL VALUE