Mitsubishi Lancer (4A9 engine). Manual — part 285

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-21

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-119 A/C control
panel connector and C-15 A/C-ECU connector

Q: Is the check result normal?

YES :

Go to Step 2.

NO :

Repair the connector.

STEP 2. Check the wiring harness between C-119
A/C control panel connector terminal No. 9 and
C-15 A/C-ECU connector terminal No. 9.

• Check the A/C control panel signal line for open

or short circuit.

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Repair the wiring harness.

STEP 3. Check whether the diagnosis code is
reset
Replace the A/C control panel, and erase the diagno-
sis code. Then check that no diagnosis code is being
set.

Q: Is the diagnosis code set?

YES :

Replace the A/C-ECU.

NO :

This diagnosis is complete.

Code No. B1021: Fan dial SW error <Vehicles without A/C>

Heater Control Panel Circuit

HEATER
CONTROL
UNIT

HEATER
CONTROL
PANEL

CPU

INTERFACE
CIRCUIT

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

ACA00851

AC612706

Connectors: C-60, C-147 <LHD>

BP

C-60 (B)

C-147

COMMENTS ON TROUBLE SYMPTOM
This code will be set when the air volume control dial
position on the AC control panel is detected as
abnormal.

PROBABLE CAUSES

• Malfunction of the heater control panel

• Damaged wiring harness or connectors

• Malfunction of the heater control unit

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-22

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-147 heater control
panel connector and C-60 heater control unit
connector

Q: Is the check result normal?

YES :

Go to Step 2.

NO :

Repair the connector.

STEP 2. Check the wiring harness between C-147
heater control panel connector terminal No. 9
and C-60 heater control unit connector terminal
No. 9.

• Check the heater control panel signal line for

open or short circuit.

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Repair the wiring harness.

STEP 3. Check whether the diagnosis code is
reset.
Replace the heater control panel, and erase the
diagnosis code. Then check that no diagnosis code
is being set.

Q: Is the diagnosis code set?

YES :

Replace the heater control unit.

NO :

The trouble can be an intermittent
malfunction (Refer to GROUP 00, How to
Cope with Intermittent Malfunction ).

Code No. B1021: Fan dial SW error <Vehicles with A/C>

A/C Control Panel Circuit

A/C-ECU

A/C
CONTROL
PANEL

CPU

INTERFACE
CIRCUIT

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

ACA00799

AC612706

Connectors: C-15, C-119 <LHD>

AE

C-15 (B)

C-119

AC612710

Connector: C-15 <RHD>

AS

C-15 (B)

AC612711

Connector: C-119 <RHD>

AG

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-23

COMMENTS ON TROUBLE SYMPTOM
This code will be set when the air volume control dial
position on the AC control panel is detected as
abnormal.

PROBABLE CAUSES

• Malfunction of the A/C control panel

• Damaged wiring harness or connectors

• Malfunction of the A/C-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-119 A/C control
panel connector and C-15 A/C-ECU connector

Q: Is the check result normal?

YES :

Go to Step 2.

NO :

Repair the connector.

STEP 2. Check the wiring harness between C-119
A/C control panel connector terminal No. 9 and
C-15 A/C-ECU connector terminal No. 9.

• Check the A/C control panel signal line for open

or short circuit.

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Repair the wiring harness.

STEP 3. Check whether the diagnosis code is
reset
Replace the A/C control panel, and erase the diagno-
sis code. Then check that no diagnosis code is being
set.

Q: Is the diagnosis code set?

YES :

Replace the A/C-ECU.

NO :

This diagnosis is complete.

Code No. B1079: A/C Refrigerant leaks

COMMENTS ON TROUBLE SYMPTOM
If this code is set, the refrigerant level may not be
appropriate, or the A/C pressure sensor may be
faulty (If this code is set, the A/C indicator will flash).

PROBABLE CAUSES

• Inadequate refrigerant level

• Malfunction of the A/C pressure sensor

• Malfunction of the ambient temperature sensor

• Damaged wiring harness or connectors

• Malfunction of the A/C-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the condenser assembly
Check that the condenser assembly is not wet.

Q: Is the check result normal?

YES :

Go to Step 2.

NO :

Wait until the condenser is dry, and check
that no diagnosis code is set.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-24

STEP 2. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Repair the CAN bus lines. (Refer to GROUP
54C, Troubleshooting ).

STEP 3. M.U.T.-III diagnosis code
Check that the diagnosis code related to the A/C is
not set.

Q: Is the diagnosis code set?

YES :

Carry out the diagnosis code procedures.

Refer to .

NO :

Go to Step 4.

STEP 4. M.U.T.-III data list
Check that the following service data display con-
tents are normal. (Refer to )

• Item 02: Ambient temperature sensor

Q: Is the check result normal?

YES :

Go to Step 5.

NO :

Refer to code No.B1011, B1012: Ambient
temperature sensor system .

STEP 5. Check the A/C pressure sensor
Refer to .

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Replace the A/C pressure sensor.

STEP 6. Refrigerant level check
Refer to .

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

Correct the refrigerant level.

STEP 7. Check whether the diagnosis code is
reset

Q: Is the diagnosis code set?

YES :

Refer to Inspection Procedure 11: A/C

pressure sensor system .

NO :

The trouble can be an intermittent
malfunction (Refer to GROUP 00, How to
Cope with Intermittent Malfunction ).

Code No. B2214: Control panel failure <Vehicles without A/C>

Heater Control Panel Circuit

HEATER
CONTROL
UNIT

HEATER
CONTROL
PANEL

CPU

INTERFACE
CIRCUIT

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

ACA00851