Mitsubishi Evolution X. Manual - part 1287

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-99

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB992006: Extra Fine Probe

•  MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: M.U.T.-III USB Cable

• MB991910: M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, check for diagnostic 
trouble code.
Check if an A/C-ECU DTC is set.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?

YES : Refer to DIAGNOSTIC TROUBLE CODE CHART 

P.55-9

.

NO :  Go to Step 2.

STEP 2. Check mode selection damper control motor 
connector C-112 and A/C-ECU connector C-20 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.
Q: Are mode selection damper control motor connector 

C-112 and A/C-ECU connector C-20 in good condition?
YES : Go to Step 3.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. Check 

that the A/C works normally. 

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-100

STEP 3. Check the wiring harness between A/C-ECU 
connector C-20 (terminal 29, 31, 32, 30 and 33) and mode 
selection damper control motor connector C-112 
(terminals 3, 2, 5. 4 and 1).
Q: Are the wiring harness between A/C-ECU connector 

C-20 (terminal 29, 31, 32, 30 and 33) and mode selection 
damper control motor connector C-112 (terminals 3, 2, 
5. 4 and 1) in good condition?
YES : Go to Step 4.
NO :  Repair the wiring harness. Check that the A/C works 

normally. 

STEP 4. Replace the mode selection damper control motor 
and check the trouble symptom again
Check the trouble symptom again.
Q: Is the check result satisfactory?

YES : The procedure is complete.
NO :  Replace the A/C-ECU.

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-101

INSPECTION PROCEDURE 9: Blower Motor power supply system.

Blower Motor Circuit

FUSIBLE
LINK

37

BLOWER
RELAY

ETACS-
ECU 

A/C-ECU

BLOWER
MOTOR

POWER
TRANSISTER

AC708621

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-102

.

TECHNICAL DESCRIPTION (COMMENT)

If the voltage is not supplied to the blower motor, the blower 
relay system may be failed.

.

TROUBLESHOOTING HINTS

• Malfunction of the ETACS-ECU

• Malfunction of the blower relay

• Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB992006: Extra Fine Probe

STEP 1. Check blower relay connector C-303 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.
Q: Is blower relay connector C-303 in good condition?

YES : Go to Step 2.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

.

AC708951AU

Connector: C-115

AC708972AT

Connectors: C-303, C-309, C-315

C-309 (B)

C-315

C-303

ETACS-ECU