Mitsubishi Galant (2004+). Manual - part 779

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-255

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

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-256

ACTUATOR TEST REFERENCE

M1554005200133

MUT-III SCAN TOOL 
DISPLAY

ITEM NO.

INSPECTION ITEM

DRIVE CONTENT

Blower fan: OFF

01

Blower motor

OFF

Blower fan: 8 step

02

Middle speed

Blower fan: 16 step

03

High speed

Air mix damper motor: 
0%

10

Air mixing damper control motor

Opening degree: approx. 
0% (Max cool)

Air mix damper motor: 
50%

11

Opening degree: approx. 
50%

Air mix damper motor: 
100%

12

Opening degree: approx. 
100% (Max hot)

Air outlet c/o damper: 
FACE

13

Mode selection damper control 
motor

FACE

Air outlet c/o damper: Bi_ 
Level

14

FOOT/FACE

Air outlet c/o damper: 
FOOT

15

FOOT

Air outlet c/o damper: 
DEF/FOOT

16

DEF/FOOT

Air outlet c/o damper: 
DEF

17

DEF

In/out changeover 
damper: Recirc

30

Outside/inside air selection damper 
control motor

Inside

In/out changeover 
damper: Fresh

31

Outside

Rear defogger switch: 
OFF

40

Rear window defogger switch

Rear window defogger: OFF

Rear defogger switch: 
ON

41

Rear window defogger: ON

Idle up request: OFF

50

Idle up operation

Idle up: OFF

Idle up request: low load 51

Idle up: low load

Idle up request: high load 52

Idle up: high load

Condenser: 0%

09

Condenser fan

OFF

Condenser: 50%

0A

Middle speed

Condenser: 100%

0B

High speed

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-257

CHECK AT A/C-ECU TERMINAL <LOW TYPE>

M1552010300561

24

30

21

272829

2223

32

31

2526

AC306430

C-10

C-09

AB

TERMINAL 
NO.

CHECK ITEM

CHECKING REQUIREMENTS NORMAL CONDITION

1

A/C pressure sensor ground

Always

0 V

2

Ground

Always

0  V

3

A/C pressure sensor

Ignition switch: ON

5 V

4

A/C pressure sensor

at 2.6 MPa

3.9 V

5, 6

−

−

−

7

Power supply to the ignition 
switch (ACC)

Ignition switch: ON

Battery positive voltage

8

Back-up power supply

Always

Battery positive voltage

9

Air mixing damper control motor When the air mix damper is 

moved to the MAX. COOL 
position. 

10 V

When the air mix damper is 
moved to the MAX. HOT 
position. 

0.5 V

10

Sensors and potentiometers 
ground

Always

0 V

11

Mode selection damper control 
motor potentiometer input

When the damper has moved to 
the DEF position. 

0.67 V

12

Air mixing damper control motor 
potentiometer input

When the damper door has 
moved to the MAX. HOT 
position. 

1.4 V

13

Air thermo sensor input

When sensor temperature is 
25

°C (77°F) [1.5 kΩ]

2.2 V

14

Ambient air temperature sensor 
input

When sensor temperature is 
25

°C (77°F) [4 kΩ]

1.9 V

15

Potentiometer power supply

Ignition switch: ON

5 V

16

Power supply to the ignition 
switch (IG2)

Ignition switch: ON

Battery positive voltage

21

ILL power supply

Lighting switch: ON

Battery positive voltage

22

Illumination ground

Always

0 V

23

A/C compressor relay

A/C compressor relay: ON

Battery positive voltage

24

Blower switch 

Ignition switch: ON
Blower switch: ON

Battery positive voltage

25, 26

−

−

−

27

Rear window defogger relay

Ignition switch: ON

Battery positive voltage

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-258

28

Outside/inside air selection 
damper control motor (outside)

When the damper flap is 
moving to the air recirculation 
position.

0.5 V

When the damper flap is 
moving to the outside air 
position.

0 V (when the motor is 
stopped)

29

Outside/inside air selection 
damper control motor (inside)

When the damper flap is 
moving to the air recirculation 
position.

0 V (when the motor is 
stopped)

When the damper flap is 
moving to the outside air 
position.

0.5 V

30

Mode selection damper control 
motor (DEF)

When the damper is moved to 
the FACE position. 

0.5 V

When the damper is moved to 
the DEF position. 

10 V

31

Mode selection damper control 
motor (FACE)

When the damper is moved to 
the FACE position. 

10 V

When the damper is moved to 
the DEF position. 

0.5 V

32

Air mixing damper control motor When the air mix damper is 

moved to the MAX. COOL 
position. 

0.5 V

When the air mix damper is 
moved to the MAX. HOT 
position. 

10 V

TERMINAL 
NO.

CHECK ITEM

CHECKING REQUIREMENTS NORMAL CONDITION