Mitsubishi Galant 9G. Manual — part 258

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-108

STEP 3. Using scan tool MB991958, check for any
diagnostic trouble code.
Check if a DTC, which relates to CAN communication-linked
systems below, is set.

• Combination meter

DTC indicating a time-out error related to the engine or
automatic transmission control system

• ETACS

DTC indicating a time-out error related to the engine or
automatic transmission control system

• Multi-center display unit (middle grade type)

DTC indicating a time-out error related to the engine or
automatic transmission control system

(1) Turn the ignition switch to the "ON" position.
(2) Check for a DTC related to the relevant system.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : Go to Step 5.
NO : Go to Step 4.

STEP 4. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : There is an intermittent malfunction such as poor

engaged connector(s) or open circuit (Refer to
GROUP 00, How to Use Troubleshooting/Inspection
Service Points

− How to Cope with Intermittent

Malfunctions

P.00-14

).

NO : Replace the powertrain control module. On

completion, check that the DTC is not reset.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-109

STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : A poor connection, open circuit or other intermittent

malfunction is present in the lines between the
powertrain control module and the A/C-ECU (Refer to
GROUP 00, How to Use Troubleshooting/Inspection
Service Points

− How to Cope with Intermittent

Malfunctions

P.00-14

.)

NO : Replace the A/C-ECU. On completion, check that the

DTC is not reset.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-110

SYMPTOM CHART <LOW TYPE>

M1552009900484

CAUTION

During diagnosis, a DTC code associated with
other system may be set when the ignition switch
is turned on with connector(s) disconnected. On
completion, confirm all systems for DTC code(s).
If DTC code(s) are set, erase them all.

SYMPTOM PROCEDURES <LOW TYPE>

INSPECTION PROCEDURE 1: When the Ignition Switch is "ON", the A/C does not Operate.

.

TECHNICAL DESCRIPTION (COMMENT)

The blower system or the compressor system may
be defective if there is no cool air coming from the
vents.

.

TROUBLESHOOTING HINTS

• Malfunction of blower motor

• Malfunction of A/C compressor

SYMPTOM

INSPECTION
PROCEDURE

REFERENCE
PAGE

When the ignition switch is "ON", the A/C does not operate.

1.

P.55A-110

When the air outlet changeover control knob is moved to DEFROSTER or
DEFROSTER/FOOT position, the A/C or the inside/outside air
changeover damper motor does not operate.

2.

P.55A-111

Outside/Inside air changeover is not possible.

3.

P.55A-112

When the A/C is operating, temperature inside the passenger
compartment does not decrease (cool air is not emitted).

4.

P.55A-118

Blower fan and motor do not turn.

5.

P.55A-137

Blower air amount cannot be changed.

6.

P.55A-149

The A/C indicator flashes.

7.

P.55A-153

Defogger function does not operate.

8.

P.55A-158

Defogger timer function does not operate.

9.

P.55A-169

Malfunction of the A/C-ECU power supply system.

10.

P.55A-170

Condenser fan does not operate.

11.

REFER TO
GROUP 14

−

SYMPTOM
CHART

P.14-3

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-111

DIAGNOSIS

Check that the blower motor operation when the blower
switch is moved to the "HI" position.
(1) Turn the ignition switch to the "ON" position.
(2) Turn the blower switch to the "4" position
Q: Does the blower motor operate when the blower switch

is moved to the "4" position?
YES : Refer to Inspection procedure 4 "When the A/C is

operating, temperature inside the passenger
compartment does not decrease (cool air not emitted)

P.55A-118

."

NO : Refer to Inspection procedure 5 "Blower fan and

motor do not turn

P.55A-137

."

INSPECTION PROCEDURE 2: When the Air Outlet Changeover Control Knob is Moved to
DEFROSTER or DEFROSTER/FOOT Position, the A/C or the Inside/outside Air Changeover Damper
Motor does not operate.

.

TECHNICAL DESCRIPTION (COMMENT)

If the outside/inside air selection damper control
motor does not operate normally, the inside/outside
air changeover damper motor system may be defec-
tive.

.

TROUBLESHOOTING HINTS

• Malfunction of the A/C-ECU

• Malfunction of the outside/inside air selection

damper control motor

• Damaged harness wires or connectors

DIAGNOSIS

Check operation of the outside/inside air selection damper
control motor.
(1) Turn the ignition switch to the "ON" position.
(2) Outside/inside air selection damper motor switch: This is

used to switch from the inside air to outside air or vice
versa.

(3) Check to see that the outside/inside air selection damper

motor operates normally.

Q: Does outside/inside air selection damper control motor

work normally?
YES : Replace the A/C-ECU.
NO : Refer to Inspection procedure 3, "Inside/outside air

changeover is not possible

P.55A-112

."