Mitsubishi Montero (2004+). Manual - part 636

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-33

NOTE: Also check junction block connectors D-220. If junction 
block connectors D-220 is damaged, repair or replace the con-
nector as described in GROUP 00E, Harness Connector 
Inspection 

P.00E-2

.

Q: Is the wiring harness between data link connector D-118 

(terminal 11, 1), A/C-ECU connector D-23 (terminal 19) 
and D-24 (terminal 33) in good condition?
YES : Replace the A/C-ECU (Refer to 

P.55B-142

). Scan 

tool MB991958 should communicate with the vehicle 
system.

NO :  Repair the wiring harness. Scan tool MB991958 

should communicate with the vehicle system.

AC204173

CONNECTOR : D-220

AI

HARNESS SIDE

1

2

3

7

8

6

5

10

4

9

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-34

INSPECTION PROCEDURE 2: Air Conditioning does not Operate.

A/C 
COMPRESSOR 
CLUTCH RELAY

IGNITION 
SWITCH (IG2)

RELAY
BOX

LOW-PRESSURE
SIDE

DUAL
PRESSURE
SWITCH

DRIVE CIRCUIT

HEATER
BLOWER
CONTROLLER
UNIT

HIGH-PRESSURE
SIDE

A/C 
COMPRESSOR 

MAGNETIC
CLUTCH

A/C-ECU

POWERTRAIN
CONTROL
MODULE

JOINT
CONNECTOR
(2)

JUNCTION
BLOCK

FUSIBLE
LINK

1

A/C Compressor Circuit

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-35

.

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

.

TROUBLESHOOTING HINTS

• Malformation of the air thermo sensor 

• Malformation of the dual pressure switch

• Malformation of the A/C compressor clutch relay

• Malformation of the A/C refrigerant temperature 

switch

• Malformation of the magnetic clutch

• Malformation of the A/C-ECU

• Malformation of the flexible flat cable

• Malformation of the automatic air-conditioning 

control panel

• Malformation of the PCM

AC204167

CONNECTORS : A-03, A-05, 
A-15, A-22

BA

A-03(B)

A-05(B)

A-15

A-22(BR)

AC204183

CONNECTOR : A-12X

AQ

AC204169

CONNECTOR : B-30

AF

B-30(B)

AC204171BD

D-134(GR)

D-17

D-132(GR)

CONNECTORS : D-17, D-132, D-134

AC204170

CONNECTORS : D-23, D-28

DW

D-28

D-23(B)

AC204173

CONNECTORS : D-208, D-210

BF

D-208

D-210

AC204176 BM

CONNECTOR : E-111

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-36

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

STEP 1. Using scan tool MB991958, read the 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.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOOK (OFF)" position.
Q: Is a diagnostic trouble code set?

YES : Refer to 

P.55B-7

.

NO :   Go to Step 2.

STEP 2. Check the defogger and outside/inside air 
changeover damper control motor operation.
Q: Do the defogger and outside/inside air changeover 

damper control motor work normally?
YES : Go to Step 3.
NO :  Refer to Inspection Procedure 11 "Malfunction does 

not operate 

P.55B-122

."

STEP 3. Check the blower motor operation.
Q: Does the blower motor work normally?

YES : Go to Step 4.
NO :  Refer to Inspection Procedure 5 "Blower Fan and 

motor does not tern 

P.55A-12

."

AC307591 AB

MB991911

DATA LINK

CONNECTOR

MB991824

MB991827