Mitsubishi Lancer (4A9 engine). Manual - part 293

AC612706

Connectors: C-15, C-109, C-110 <LHD>

AF

C-15 (B)

C-109

C-110

AC612710

Connectors: C-15, C-109, C-110 <RHD>

AT

C-15 (B)

C-109

C-110

AC612709

Connector: C-303<LHD>

AO

ETACS-ECU

AC612717

Connector: C-303 <RHD>

AO

ETACS-ECU

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-53

COMMENTS ON TROUBLE SYMPTOM
If the blower motor does not operate, the blower 
motor circuit system may be defective.

PROBABLE CAUSES

• Malfunction of the blower motor

• Malfunction of the power transistor

• Malfunction of the A/C-ECU

• Damaged wiring harness or connectors

DIAGNOSIS PROCEDURE

STEP 1. 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 2.

NO : 

Repair the CAN bus lines (Refer to GROUP 
54C 

− Troubleshooting ).

STEP 2. M.U.T.-III diagnosis code.
Recheck if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition switch: LOCK (OFF) to ON
(3) Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Carry out the diagnosis code procedures. 

Refer to . 

NO : 

Go to Step 3.

STEP 3. Connector check: C-303 blower relay 
connector

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the connector.

STEP 4. Check the blower relay.
Refer to .

Q: Is the blower relay in good condition?

YES : 

Go to Step 5.

NO : 

Replace the blower relay.

STEP 5. Connector check: C-110 blower motor 
connector

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the connector.

STEP 6. Check the blower motor.
Refer to .

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Replace the blower motor.

STEP 7. Voltage measurement at C-110 blower 
motor connector.
(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Turn the ignition switch to the ON position.
(3) Voltage between terminal 1 and body earth. 

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-54

<LHD>

OK: System voltage

(4) Voltage between terminal 2 and body earth. 

<RHD>

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

INSPECTION PROCEDURE 14: Refer to 
"Blower motor power supply system" .

STEP 8. Connector check: C-109 power 
transistor controller connector

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Repair the connector.

STEP 9. Resistance measurement at the C-109 
power transistor connector.
(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Continuity between terminal 1 and body earth

OK: Continuity exists (2 

Ω or less)

Q: Is the check result normal?

YES : 

Go to Step 10.

NO : 

Repair the wiring harness wires between 
power transistor connector terminal No. 1 
and body earth.

STEP 10. Check the wiring harness between C-
110 blower motor connector terminal No.2 <LHD> 
or 1 <RHD> and C-109 power transistor 
connector terminal No.2.

• Check the power transistor power supply line for 

open circuit.

Q: Is the check result normal?

YES : 

Go to Step 11.

NO : 

Repair the wiring harness.

STEP 11. Connector check: C-15 A/C-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 12.

NO : 

Repair the connector.

STEP 12. Check the wiring harness between C-
110 blower motor connector terminal No.2 <LHD> 
or 1 <RHD> and C-15 A/C-ECU connector 
terminal No.1.

• Check the blower motor power supply line for 

open circuit.

Q: Is the check result normal?

YES : 

Go to Step 13.

NO : 

Repair the wiring harness.

STEP 13. Check the wiring harness between C-
109 power transistor connector terminal No.4 
and C-15 A/C-ECU connector terminal No.2.

• Check the power transistor power supply line for 

open circuit.

Q: Is the check result normal?

YES : 

Go to Step 14.

NO : 

Repair the wiring harness.

STEP 14. Check the wiring harness between C-15 
A/C-ECU connector terminal No.14 and body 
earth.

• Check the power transistor power supply line for 

open circuit.

Q: Is the check result normal?

YES : 

Go to Step 15.

NO : 

Repair the wiring harness.

STEP 15. Replace the power transistor and 
recheck the trouble symptom
Check that the blower motor operates normally.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the A/C-ECU.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-55

INSPECTION PROCEDURE 4: The blower air volume cannot be changed

Blower Motor Circuit

FUSIBLE
LINK

37

BLOWER
RELAY

ETACS-
ECU 

A/C-ECU

BLOWER
MOTOR

POWER
TRANSISTOR

NOTE

: LHD
: RHD

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

FUSIBLE
LINK

42

<4N1>

<4A9, 4J1, 4B1>

ACB02688

AC612706

Connectors: C-15, C-109, C-110 <LHD>

AF

C-15 (B)

C-109

C-110

AC612710

Connectors: C-15, C-109, C-110 <RHD>

AT

C-15 (B)

C-109

C-110

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-56

COMMENTS ON TROUBLE SYMPTOM
If air volume cannot be adjusted by using the blower 
control, the A/C control panel, the A/C-ECU or the 
power transistor may be faulty.

PROBABLE CAUSES

• Malfunction of the A/C control panel

• Malfunction of the power transistor

• Damaged wiring harness or connectors

• Malfunction of the A/C-ECU

DIAGNOSIS PROCEDURE

STEP 1. 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 2.

NO : 

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

STEP 2. M.U.T.-III diagnosis code
Check that the diagnosis code related to the air con-
ditioner is not set.

Q: Is the diagnosis code set?

YES : 

Carry out the diagnosis code procedures. 

Refer to .

NO : 

Go to Step 3.

STEP 3. Connector check: C-109 power 
transistor controller connector

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the connector.

STEP 4. Resistance measurement at the C-109 
power transistor connector.
(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Continuity between terminal 1 and body earth

OK: Continuity exists (2 

Ω or less)

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the wiring harness wires between 
power transistor connector terminal No. 1 
and body earth.

STEP 5. Connector check: C-15 A/C-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the connector.

STEP 6. Check the wiring harness between C-110 
blower motor connector terminal No.2 <LHD> or 
1 <RHD> and C-15 A/C-ECU connector terminal 
No.1.

• Check the blower motor earth line for open cir-

cuit.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Repair the wiring harness.

STEP 7. Check the wiring harness between C-109 
power transistor connector terminal No.4 and C-
15 A/C-ECU connector terminal No.2.

• Check the blower motor earth line for open cir-

cuit.

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

Repair the wiring harness.

STEP 8. Check the wiring harness between C-15 
A/C-ECU connector terminal No.14 and body 
earth.

• Check the power transistor power supply line for 

open circuit.

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Repair the wiring harness.