Mitsubishi Colt Ralliart. Manual — part 665

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-21

Inspection Procedure 3: The blower air volume cannot be changed

BLOWER
RELAY

POWER
TRANSISTER

BLOWER
MOTOR

COMBINATION
METER

BLOWER MOTOR
DRIVE CIRCUIT

METER AND A/C-ECU

Wire colour code
B : Black LG : Light green G : Green L : Blue W : White Y : Yellow SB : Sky blue
BR : Brown O : Orange GR : Gray R : Red P : Pink V : Violet

Blower Motor Circuit

COMMENTS ON TROUBLE SYMPTOM

If the blower air volume can not be changed when
the blower switch is operated, the circuit between
power transistor and combination meter (meter and
A/C-ECU) may be defective.

POSSIBLE CAUSES

• Front power transistor

• Damaged the wiring harness or connectors

• Malfunction of the combination meter (meter and

A/C-ECU)

Step 1. M.U.T.-III actuator test
Carry out the actuator test. (Refer to

P.55B-25

).

• Item 01, 02, 03: Blower motor

Q: Does the blower motor work normally?

YES :

Go to Step 2.

NO :

Go to Step 3.

Step 2. Replace the power transistor and check
the trouble symptom
Check that the front blower motor operates normally.

Q: Does the blower motor work normally?

YES :

This diagnosis is complete.

NO :

Replace the combination meter (meter and
A/C-ECU)

Main

Index

Group

TOC

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-22

Step 3. Connector check: B-05 power transistor
controller connector

AC313820AL

Connector: B-05

Harness side

B-05 (B)

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Repair the connector.

Step 4. Resistance measurement at the B-05
power transistor connector.

AC313820AL

Connector: B-05

Harness side

B-05 (B)

(1) Disconnect the connector, and measure at the

wiring harness side.

AC310506

Connector B-05
(Harness side)

EH

(2) Continuity between terminal 5 and body earth

OK: Continuity (Less than 2

Ω)

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Go to Step 5.

Step 5. Check the wiring harness between B-05
power transistor connector terminal No.5 and
body earth.

AC313820AL

Connector: B-05

Harness side

B-05 (B)

• Check the blower linear controller earth line for

open circuit.

Q: Is the check result normal?

YES :

The trouble can be an intermittent

malfunction (Refer to GROUP 00, How to
Cope with Intermittent Malfunction

P.00-13

).

NO :

Repair the wiring harness.

Step 6. Connector check: B-15 combination
meter controller connector

AC313822 AB

Connector: B-15

Harness side

B-15 (B)

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

Repair the connector.

Main

Index

Group

TOC

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-23

Step 7. Check the wiring harness between B-15
combination meter connector (terminals 19 and
20) and B-05 power transistor controller
connector (terminals 1 and 3).

AC313820AL

Connector: B-05

Harness side

B-05 (B)

AC313822 AB

Connector: B-15

Harness side

B-15 (B)

• Check the blower linear controller power supply

line for open circuit.

Q: Is the check result normal?

YES :

Go to Step 8.

NO :

Repair the wiring harness.

Step 8. Replace the power transistor and check
the trouble symptom
Check that the front blower motor operates normally.

Q: Does the blower motor work normally?

YES :

This diagnosis is complete.

NO :

Replace the combination meter (meter and
A/C-ECU).

Main

Index

Group

TOC

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-24

SERVICE DATA REFERENCE TABLE

M1554005100288

Item No.

Check items

Check contents

01

Interior temperature sensor Ignition switch: ON

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

02

Ambient temperature sensor Ignition switch: ON

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

03

Air thermo sensor

Ignition switch: ON

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

04

A/C pressure sensor

Ignition switch: ON

According with the chart for
simple inspection of the A/C
pressure sensor (Refer to
GROUP 55A, On-vehicle
Service

P.55A-51

).

05

Water temperature sensor

Ignition switch: ON

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

06

Photo sensor

Ignition switch: ON
Change the volume of
insolation.

The amount of solar radiation
is indirectly proportional to
M.U.T.-III displayed voltage

07

Set temperature

Ignition switch: ON

Displays the set temperarure

08

Set temperature (control
part set value)

Ignition switch: ON

Display the control part set
temperarure

10

Air mixing damper control
motor and potentiometer

Ignition switch: ON
Damper position: MAX HOT

Opening angle: 100%

Ignition switch: ON
Damper position: MAX
COOL

Opening angle: approximately
0%

11

Air mixing damper control
motor and potentiometer
(Target)

Ignition switch: ON

Display the target value for air
mix damper

15

Outside/Inside air selection
damper

Ignition switch: ON

Display the outside/inside air
selection damper position

20

Blower motor

Ignition switch: ON

Display the rotation speed of
blower motor

21

Blower motor (Target)

Ignition switch: ON

Display the target rotation
speed of blower motor

30

A/C switch

Ignition switch: ON

Display the A/C switch status

31

A/C switch (control part set
value)

Ignition switch: ON

A/C switch status

35

Rear window defogger
switch (control part set
value)

Ignition switch: ON

Display the rear window
defogger switch status

36

Blower switch

Ignition switch: ON

Display the blower switch
status

Main

Index

Group

TOC