Mitsubishi Lancer (4A9 engine). Manual — part 300

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-81

(4) Voltage between terminal 1 and body earth

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 27.

NO :

Go to Step 21.

STEP 21. Measure the voltage at A-23X PTC
heater relay3 connector.
(1) Remove the relay, and measure at the relay side.
(2) Voltage between terminal 4 and body earth

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 23.

NO :

Go to Step 22.

STEP 22. Check the wiring harness between A-
23X PTC heater relay3 connector terminal No. 4
and fusible link (41) connector.

• Check the power supply line for open circuit.

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Use Troubleshooting/

Inspection Service Points - How to Cope
with Intermittent Malfunction ).

NO :

Repair the wiring harness.

STEP 23. Measure the voltage at A-23X PTC
heater relay3 connector.
(1) Remove the relay, and measure at the relay side.
(2) Turn the ignition switch to the "ON" earth position.
(3) Voltage between terminal 1 and body earth

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 25.

NO :

Go to Step 24.

STEP 24. Check the wiring harness between A-
23X PTC heater relay3 connector terminal No. 1
and C-317 ETACS-ECU connector terminal No. 5.
NOTE: Prior to the wiring harness inspection, check
intermediate connector C-128, and repair if neces-
sary.

• Check the power supply line for open circuit.

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Use Troubleshooting/

Inspection Service Points - How to Cope
with Intermittent Malfunction ).

NO :

Repair the wiring harness.

STEP 25. Check the wiring harness wires
between C-52 PTC heater connector terminal No.
1 and A-23X PTC heater relay3 connector
terminal No. 3.

• Check the power supply line for open circuit.

Q: Is the check result normal?

YES :

Go to Step 26.

NO :

Repair the wiring harness.

STEP 26. Check the wiring harness between A-
23X PTC heater relay3 connector terminal No. 2
and C-15 A/C-ECU connector terminal No. 5.
NOTE: Prior to the wiring harness inspection, check
intermediate connector C-127, and repair if neces-
sary.

• Check the power supply line for open circuit.

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Use Troubleshooting/

Inspection Service Points - How to Cope
with Intermittent Malfunction ).

NO :

Repair the wiring harness.

STEP 27. Connector check: C-53 PTC heater
connector

Q: Is the check result normal?

YES :

Go to Step 28.

NO :

Repair the connector.

STEP 28. Resistance measurement at C-53 PTC
heater connector.
(1) Disconnect the connector, and measure at the

wiring harness side.

(2) Continuity between terminal 1, 2 and body earth.

OK: Continuity (Less than 2 ohms)

Q: Is the check result normal?

YES :

Go to Step 30.

NO :

Go to Step 29.

STEP 29. Check the wiring harness between C-53
PTC heater connector (terminals 1 and 2) and
body earth.

• Check the PTC heater earth line for open circuit.

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Use Troubleshooting/

Inspection Service Points - How to Cope
with Intermittent Malfunction ).

NO :

Repair the wiring harness.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-82

STEP 30. Check the PTC heater.
Refer to .

Q: Is the check result normal?

YES :

Replace the A/C-ECU.

NO :

Replace the PTC heater.

DATA LIST REFERENCE TABLE

M1554005101032

Item No.

Check item

Inspection status

The display contents
under normal condition

17

Engine speed

−

Displays correct engine
speed.

19

Ambient temperature
sensor

−

Ambient temperature is the
same as M.U.T.-III
displayed temperature

20

Air thermo sensor

−

Evaporator outlet
temperature is the same as
M.U.T.-III displayed
temperature.

21

Interior temperature
sensor

−

Interior temperature is the
same as M.U.T.-III
displayed temperature

23

Temperature setting

Displays air conditioner set
temperature.

24

Engine coolant TEMP
sensor

−

Engine coolant temperature
is the same as M.U.T.-III
displayed temperature.

26

Vehicle speed

−

Displays vehicle speed.

27

A/C Compressor drive
request

Compressor ON

ON

Compressor OFF

OFF

28

Air conditioning switch

Air conditioner switch ON

ON

Air conditioner switch OFF

OFF

29

Refrigerant leak

−

Normal

34

Idle up request

−

Displays idle-up request
signal.

45

In/out select damper
poten (target)

−

Displays outside/inside air
selection damper target
position.

46

In/out select damp
potentiometer

−

Displays outside/inside air
selection damper position.

55

Air outlet c/o
potentiometer

−

Displays air outlet
changeover damper
position.

56

Air outlet c/o potentio.
(Target)

−

Displays air outlet
changeover damper target
position.

57

Low pressure

−

Normal

60

Rear defogger switch

Rear window defogger switch ON

ON

Rear window defogger switch OFF

OFF

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-83

61

Pressure sensor

−

Displays refrigerant
pressure.

63

Air mix potentiometer

−

Displays the air mix damper
position.

67

Photo sensor

−

Displays sunload.

68

Front blower fan

−

Displays blower motor
condition.

69

Front blower fan
(Target)

−

Displays blower motor
target value.

73

Refrigerant pressure

−

Displays refrigerant
pressure status.

74

Condenser fan

−

Displays condenser fan
running condition.

76

Temp. set dial position

−

Displays the set
temperature output value
on the control panel.

77

A/C Panel type

−

Displays as same as the
specification.

78

Fan set dial position

−

Displays the air volume
output value on the control
panel.

79

Air outlet c/o set dial
position

−

Displays output value to the
air outlet changeover dial
on the control panel.

80*

Fan set dial operation
flag

−

ON when the air volume
adjusting dial is operated

81*

A/C SW operation flag

−

ON when the air conditioner
switch is operated

82*

Temp. set dial operation
flag

−

ON when the air conditioner
switch is operated

83*

Defogger flag

−

ON when the air outlet
changeover dial is set to the
DEF position.

84*

In/out air c/o SW
operation flag

−

ON when the inside air/
outside air changeover
switch is operated

87*

Rear defogger SW
operation flag

−

ON when the rear window
switch is operated

88

Rear defogger SW lamp −

Displays rear window
switch indicator status.

89

A/C SW lamp

−

Displays air conditioner
switch indicator status.

Item No.

Check item

Inspection status

The display contents
under normal condition

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-84

NOTE: *: The display may not switch if the switch
operation timing does not correspond to the M.U.T.-
III readout timing.

ACTUATOR TEST TABLE

M1554005201200

Item No.

Check item

Driven content

2

Idle up request*

Idle-up request signal

5

In/out selection damper

The moving position of outside/inside air
selection damper motor

6

Air mix damper motor

The moving position of air mix damper
motor

7

Front blower fan

The amount of blower motor rotation

8

Air outlet c/o damper

Air outlet changeover damper motor
moving position

10

Condenser fan*

The amount of condenser fan rotation

11

Air conditioner*

A/C switch selection position

12

Rear defogger switch*

Rear window defogger switch selection
position

NOTE: *: When the engine is not running these func-
tion do not work.

CHECK AT A/C-ECU TERMINALS

M1552010302675

32

24

29

21

31

30

2223

27

35

33

25

34

26

36

28

AC507400

<C-15 (Vehicles with A/C)>

<C-13 (Vehicles with A/C)>

AN

<C-60 (Vehicles without A/C)>

<C-59 (Vehicles without A/C)>

90

In/out air c/o SW lamp

−

Displays the status of the
inside air/outside air
changeover switch
indicator.

91

A/C Compressor drive
flag

−

ON when the compressor is
activated.

92

Wiper operation flag

−

ON when the wiper is
operated.

93

Ignition position
information

−

Ignition switch position
status

94

Power source voltage

−

Displays power supply
voltage.

95

IOD fuse equipment
flag

−

IOD fuse status

Item No.

Check item

Inspection status

The display contents
under normal condition

Terminal
No.

Check item

Check condition

Normal condition

1

Power transistor (DRAIN)

Air volume control dial: Maximum air
volume

0 to 2 V

2

Power transistor (GATE)

Air volume control dial: Maximum air
volume

System voltage

3

− 8

−

−

−