Mitsubishi Evolution X. Manual - part 1285

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-91

.

CIRCUIT OPERATION

If the blower motor speed cannot be changed, the power tran-
sistor circuit is suspected.

.

TROUBLESHOOTING HINTS

• Malfunction of the power transistor

• Malfunction of the A/C-ECU

• Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB992006: Extra Fine Probe

STEP 1. Check power transistor connector C-119 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.
Q: Is power transistor connector C-119 in good condition?

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

00E, Harness Connector Inspection 

P.00E-2

.The 

blower motor should operate normally.

STEP 2. Measure the resistance at power transistor 
connector C-119.
(1) Disconnect power transistor connector C-119, and measure 

the resistance at the wiring harness side.

(2) Measure the resistance value between terminal 1 and 

ground.

OK: The measured value should be 2 ohms or less

Q: Does the measured resistance value correspond with 

this range?
YES :  Go to Step 4.
NO :   Go to Step 3.

AC708951AQ

Connectors: C-22, C-119

C-119

C-22 (B)

AC608255 BT

Connector C-119
(Harness side)

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-92

STEP 3. Check the wiring harness between power transitor 
connector C-119 (terminal 1) and ground.
Q: Is the wiring harness between power transitor 

connector C-119 (terminal 1) and ground in good 
condition?
YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunctions 

P.00-15

.

NO :  Repair the wiring harness. The blower motor should 

operate normally.

STEP 4. Check A/C-ECU connector C-22 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.
Q: Is A/C-ECU connector C-22 in good condition?

YES : Go to Step 5.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

.The 

blower motor should operate normally.

STEP 5. Check the wiring harness between A/C-ECU 
connector C-22 (terminals 1 and 2) and power transitor 
connector C-119 (terminals 2 and 4).
Q: Is the wiring harness between A/C-ECU connector C-22 

(terminals 1 and 2) and power transitor connector C-119 
(terminals 2 and 4) in good condition?
YES : Go to Step 6.
NO :  Repair the wiring harness. The blower motor should 

operate normally.

STEP 6. Replace the power transistor 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

55-93

INSPECTION PROCEDURE 6: Outside/Inside Air Changeover is not possible.

.

CIRCUIT OPERATION

If the outside/inside air selection damper control motor does not 
operate normally, the outside/inside air selection damper con-
trol motor system may be defective.

.

TROUBLESHOOTING HINTS

• Malfunction of the outside/inside air selection damper con-

trol motor

• Malfunction of the A/C-ECU

• Damaged harness wires or connectors

Outside/Inside Damper Control Motor Circuit

OUTSIDE/INSIDE AIR
SELECTION DAMPER 
CONTROL MOTOR

A/C-ECU

AC708622

AC708951AR

C-20 (B)

Connectors: C-20, C-111

C-111

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-94

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.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
Check if an A/C-ECU DTC is set.
(1) Connect scan tool MB991958. Refer to "How to connect the 

Scan Tool (M.U.T.-III) 

P.55-7

."

(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 outside/inside air selection damper control 
motor connector C-111 and A/C-ECU connector C-20 for 
loose, corroded or damaged terminals, or terminals 
pushed back in the connector.
Q: Are outside/inside air selection damper control motor 

connector C-111 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