Mitsubishi Lancer Evolution IX. Manual - part 539

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-29

TROUBLE SYMPTOM CHART

M1554005000571

SYMPTOM PROCEDURES

Inspection Procedure 1: Communication with the M.U.T.-II/III is not Possible.

Symptom

Inspection 
procedure number

Reference page

Communication with the M.U.T.-II/III is not possible.

1

P.55-29

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

2

P.55-32

A/C outlet air temperature cannot be set. 

3

P.55-41

The blower does not work.

4

P.55-42

The blower air volume cannot be changed.

5

P.55-54

When sunlight intensity changes, blower air 
temperature does not change.

6

P.55-56

The outside/inside air changeover is impossible.

7

P.55-58

Rear window defogger function does not operate.

8

P.55-63

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

9

P.55-73

A/C compressor power supply system.

10

P.55-79

Condenser fan does not operate.

11

P.55-86

Diagnosis Connector 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

A/C-ECU

<LHD>
<RHD>

DIAGNOSIS 
CONNECTOR

FRONT SIDE

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-30

COMMENTS ON TROUBLE SYMPTOM

If communication with all other systems is not possi-
ble, there is a high possibility that there is a malfunc-
tion of the diagnosis line. If only the A/C system can 
not communicate with the M.U.T.-II/III, the diagnosis 
line between the A/C-ECU and the diagnosis con-
nector may be defective.

PROBABLE CAUSES

• Damaged the wiring harness or connectors

• Malfunction of the automatic A/C control panel 

(A/C-ECU)

DIAGNOSIS PROCEDURE

STEP 1. Check the communication with other 
systems.

Q: Is the communication with the other systems 

possible using the M.U.T.-II/III?
YES : 

Go to Step 2.

NO : 

Check the diagnosis line using the 
M.U.T.-II/III, and repair if necessary.

STEP 2. Check operations of the A/C, rear 
window defogger and outside/inside air selection 
damper control motor.

Q: Does the A/C, rear window defogger or 

outside/inside air selection damper control motor 
operate?
YES : 

Go to Step 3.

NO : 

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

P.55-73

."

STEP 3. Connector check: C-36 A/C-ECU 
connector and C-14 diagnosis connector

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the connector.

AC504641AD

Connector: C-14, C-36 <LHD>

Harness side

C-36

C-14

C-36 (B)

C-14

AC504625AE

Connector: C-14 <RHD>

Harness side

C-14 (B)

AC504618AJ

Connector: C-36 <RHD>

Harness side

C-36 (B)

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-31

STEP 4. Check the wiring harness between C-36 
A/C-ECU connector (terminal 17 and 18) and C-14 
diagnosis connector (terminal 11 and 1).

NOTE: 

Prior to the wiring harness inspection, check joint 
connector C-23 <LH drive vehicles> or C-21 <RH 
drive vehicles> , and repair if necessary.

• Check the communication lines for open or short 

circuit.

Q: Is the check result normal?

YES : 

Replace the automatic A/C control panel 

(A/C-ECU).

NO : 

Repair the wiring harness.

AC504641AD

Connector: C-14, C-36 <LHD>

Harness side

C-36

C-14

C-36 (B)

C-14

AC504625AE

Connector: C-14 <RHD>

Harness side

C-14 (B)

AC504618AJ

Connector: C-36 <RHD>

Harness side

C-36 (B)

AC504618AM

Connector: C-21 <RHD>

AC504622AG

Connector: C-23 <LHD>

C-23 (B)

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-32

Inspection Procedure 2: When the A/C is Operating, Temperature Inside the Passenger Compartment 
does not Decrease (Cool Air is not Emitted).

A/C-ECU System 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

A/C-ECU

DUAL
PRESSURE
SWITCH

LOW-
PRESSURE
SIDE

HIGH-
PRESSURE
SIDE

BLOWER LINER
CONTROLLER

ENGINE-ECU

AIR THERMO
SENSOR