Mitsubishi Lancer Evolution IX. Manual — part 540

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-33

COMMENTS ON TROUBLE SYMPTOM

If cool air is not distributed when the A/C switch is on,
the air thermo sensor or the A/C compressor relay
system may be defective.

PROBABLE CAUSES

• Improper amount of refrigerant

• Malfunction of the air thermo sensor

• Malfunction of the dual pressure switch

• Malfunction of the A/C compressor relay

• Malfunction of the A/C refrigerant temperature

switch

• Malfunction of the magnetic clutch

• Malfunction of the manual air conditioner control

panel (A/C-ECU)

• Damaged the wiring harness or connectors

• Malfunction of the engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the rear window defogger and
outside/inside air selection damper control motor
operation.

Q: Do the rear window defogger and outside/inside air

selection damper control motor work normally?
YES :

Go to Step 2.

NO :

Refer to Inspection procedure 9
"Malfunction of the A/C-ECU power supply
system

P.55-73

."

STEP 2. Check the blower motor operation.

Q: Does the blower motor work normally?

YES :

Go to Step 3.

NO :

Refer to Inspection procedure 4 "The blower
does not work

P.55-42

."

STEP 3. Check the A/C compressor.
Check the A/C compressor for compressor oil leaks.

Q: Is the check result satisfactory?

YES :

Go to Step 4.

NO :

Replace the A/C compressor or the
expansion valve.

STEP 4. Connector check: A-36 A/C compressor
connector and C-121 engine-ECU connector

Q: Is the check result normal?

YES :

Go to Step 5.

NO :

Repair the connector.

AC504616AB

Connector: A-36

A-36 (B)

Harness side

AC504617AB

Connector: C-121 <LHD>

C-121 (GR)

Harness side

AC504618AB

Connector: C-121 <RHD>

Harness side

C-121 (GR)

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-34

STEP 5. Voltage measurement at the A-36 A/C
compressor connector.

(1) Disconnect the connector, and measure at the

wiring harness side.

(2) Disconnect engine-ECU connector C-121, and

earth terminal 20.

(3) Turn the ignition switch to the "ON" position.

(4) Measure the voltage between terminal 1 and

body earth.

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Refer to Inspection procedure 10 "A/C
Compressor power supply system

P.55-79

."

AC504616AB

Connector: A-36

A-36 (B)

Harness side

AC504617AB

Connector: C-121 <LHD>

C-121 (GR)

Harness side

AC504618AB

Connector: C-121 <RHD>

Harness side

C-121 (GR)

AC504619

Connector C-121
(Harness side)

AB

AC301541GC

Connector A-36
(Harness side)

1

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-35

STEP 6. Connector check: C-36 A/C-ECU
connector and C-34 blower liner controller
connector

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

Repair the connector.

STEP 7. Check the wiring harness between C-34
blower liner controller connector terminal No.5
and C-36 A/C-ECU connector terminal No.2.

Q: Is the check result normal?

YES :

Go to Step 8.

NO :

Repair the wiring harness.

AC504617AC

Connector: C-34 <LHD>

Harness side

AC504624AB

Connectors: C-34, C-36 <RHD>

Harness side

C-34

C-36 (B)

C-34

C-36

AC504622AB

Connector: C-36 <LHD>

Harness side

C-36 (B)

AC504617AC

Connector: C-34 <LHD>

Harness side

AC504624AB

Connectors: C-34, C-36 <RHD>

Harness side

C-34

C-36 (B)

C-34

C-36

AC504622AB

Connector: C-36 <LHD>

Harness side

C-36 (B)

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-36

STEP 8. Connector check: A-25 dual pressure
switch connector

Q: Is the check result normal?

YES :

Go to Step 9.

NO :

Repair the connector.

STEP 9. Check the dual pressure switch
operation.
Refer to

P.55-104

.

Q: Is the dual pressure switch operating properly?

YES :

Go to Step 10.

NO :

Replace the dual pressure switch.

STEP 10. Connector check: C-35 air thermo
sensor connector

Q: Is the check result normal?

YES :

Go to Step 11.

NO :

Repair the connector.

STEP 11. Check the wiring harness between C-35
air thermo sensor connector (terminals 4 and 5)
and C-36 A/C-ECU connector (terminals 8 and
10).

AC504616AC

Connector: A-25

Harness side

A-25 (BR)

AC504617AD

Connector: C-35 <LHD>

Harness side

AC504618AD

Connector: C-35 <RHD>

Harness side

AC504617AD

Connector: C-35 <LHD>

Harness side

AC504624AC

Connectors: C-35, C-36 <RHD>

Harness side

C-35

C-36 (B)

C-35

C-36

AC504622AB

Connector: C-36 <LHD>

Harness side

C-36 (B)