Mitsubishi Galant 9G. Manual — part 251

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

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DIAGNOSIS

Required Special Tool:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A (Vehicles with CAN

communication system)

STEP 1. Using scan tool MB991958, diagnose the CAN bus
line.
Use scan tool MB991958 to diagnose the CAN bus lines.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to "ON" position.
(3) Diagnose the CAN bus line.
Q: Is the check result satisfactory?

YES : Go to Step 2.
NO : Repair the CAN bus lines. (Refer to GROUP 54C,

Diagnosis-Can Bus Diagnostic Chart

P.54C-607

).

Then go to Step 7.

STEP 2. Recheck for diagnostic trouble code.
Recheck if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "ON" position.
(3) Check if the DTC is set.
Q: Is the check result satisfactory?

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 : Go to Step 3.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

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STEP 3. Using scan tool MB991958, check actuator test
item 10, 11, 12: air mix damper motor.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Start the engine.
(3) Use scan tool MB991958 to run the actuator test.

Item 10: air mix damper motor (MAX COOL position)
Item 11: air mix damper motor (middle position)
Item 12: air mix damper motor (MAX HOT position)

• Check that the air mixing damper control motor oper-

ates.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Does the motor operate normally?

YES : Replace the A/C-ECU. Then go to Step 7.
NO : Go to Step 4.

STEP 4. Check A/C-ECU connector C-15 and air mixing
damper control motor and potentiometer connector C-105
for loose, corroded or damaged terminals, or terminals
pushed back in the connector.
Q: Are A/C-ECU connector C-15 and air mixing damper

control motor and potentiometer connector C-105 in
good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Refer to GROUP

00E, Harness Connector Inspection

P.00E-2

. Then go

to Step 7.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305234

HARNESS SIDE

C-15

AJ

CONNECTORS: C-15, C-105

C-105

HARNESS SIDE

C-105

C-15 (B)

MANUAL A/C DIAGNOSIS

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STEP 5. Check the wiring harness between A/C-ECU
connector C-15 (terminals 1 and 2) and air mixing damper
control motor and potentiometer connector C-105
(terminals 1 and 2).
Q: Are the wiring harness between A/C-ECU connector

C-15 (terminals 1 and 2) and air mixing damper control
motor and potentiometer connector C-105 (terminals 1
and 2) in good condition?
YES : Go to Step 6.
NO : Repair the wiring harness. Then go to Step 7.

AC305234

HARNESS SIDE

C-15

AJ

CONNECTORS: C-15, C-105

C-105

HARNESS SIDE

C-105

C-15 (B)

MANUAL A/C DIAGNOSIS

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STEP 6. Check the air mixing damper control motor and
potentiometer.

CAUTION

Do not apply battery voltage when the damper is in the
MAX COOL or MAX HOT position.
Check the air mix damper control motor by the following proce-
dures.

Q: Are the air mixing damper control motor and

potentiometer in good condition?
YES : Repair the A/C-ECU. Then go to Step 7.
NO : Replace the air mixing damper control motor and

potentiometer. Then go to Step 7.

LEVER POSITION BATTERY

CONNECTION

LEVER
OPERATION

At the MAX COOL
position

• Connect

terminal 2 to the
positive battery
terminal

• Connect

terminal 1 to the
negative battery
terminal

The lever moves
from the MAX
COOL position to
the MAX HOT
position

At the MAX HOT
position

• Connect

terminal 1 to the
positive battery
terminal

• Connect

terminal 2 to the
negative battery
terminal

The lever moves
from the MAX HOT
position to the MAX
COOL position

AC206296

MAX HOT POSITION

MAX COOL POSITION

1 2

4

3

5

7

6

AB