Mitsubishi Montero (2004+). Manual - part 594

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-19

3

air thermo sensor power 
supply

Ignition switch and A/C switch: OFF

0 V

Ignition switch and A/C switch: ON

5 V

4

Request signal for 
tuning the A/C 
compressor

Dual pressure switch: ON

0 V

Dual pressure switch: OFF

Battery positive voltage

5

PSM communication 
line

When the A/C is OFF

0 V

When the A/C (compressor) is 
operating

Battery positive voltage

6

Defogger relay

Defogger switch: ON

0 V

Defogger switch: OFF

Battery positive voltage

7

A/C  switch 
(inside/outside)

Inside: ON

Battery positive voltage

Outside: ON

0 V

8

Defroster switch (FOOT) Defroster switch FOOT position

10 V

9

Defroster switch (DEF)

Defroster switch DEF position

10 V

10

A/C switch (A/C switch) A/C switch: ON

0 V

A/C switch: OFF

10 V

11

Ground

At all times

0 V

13

Indicator (inside/outside 
switch)

When inside /outside switch is ON

0 V

14

Indicator (A/C switch)

When A/C switch is ON

0 V

15

Indicator (defogger 
switch)

When defogger switch is ON

0 V

16

Inside/outside air 
changeover damper 
motor (inside)

When the damper flap is moving to the 
inside air recirculation position

0.5 V

When the damper flap is moving to the 
outside air recirculation position

10 V (when the motor is 
stopped)

17

Inside/outside air 
changeover damper 
motor (outside)

When the damper flap is moving to the 
outside air recirculation position

0.5 V

When the damper flap is moving to the 
inside air recirculation position

10 V (when the motor is 
stopped)

18

Backup power supply

At all times

Battery positive voltage

19

Blower switch (LO)

Blower switch LO position

Battery positive voltage

20

Defogger switch

Defogger switch: ON

0 V

Defogger switch: OFF

10 V

21

A/C compressor clutch 
relay

A/C compressor clutch relay: ON

Battery positive voltage

A/C compressor clutch relay: OFF

0 V

22

A/C compressor lock 
signal (ignition signal)

Engine speed: 3,000 r/min

0.3 

− 3.0 V

23

Lock sensor power 
supply

Ignition switch ON

5 V

24

Ground to the lock 
sensor

At all times

0 V

TERMINAL 
NO.

INSPECTION ITEM

INSPECTION REQUIREMENT

NORMAL CONDITION

REAR AIR CONDITIONING DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-20

REAR AIR CONDITIONING DIAGNOSIS

INTRODUCTION

M1554006200040

REAR AIR CONDITIONING SYSTEM

The rear air conditioning system is located behind 
the quarter trim (RH), and supplies inside air to the 
evaporator through the blower motor. Then the evap-
orator cools the inside air. The cooled inside air is 
partially warmed by the heater core according to the 
driver's control, and then will be emitted through the 
air vents. The A/C control unit selects the air vents by 
operating the mode selection damper motor accord-
ing to the temperature control knob.

TROUBLESHOOTING STRATEGY

M1554004700038

Use these steps to plan your diagnostic strategy. If 
you follow them carefully, you will be sure that you 
have exhausted most of the possible ways to find a 
heater, air conditioning and ventilation fault.
1. Gather information from the customer.

2. Verify that the condition described by the 

customer exists.

3. Find the malfunction by following the Symptom 

Chart.

4. Verify malfunction is eliminated.

SYMPTOM CHART

M1554005000236

SYMPTOM

INSPECTION 
PROCEDURE NO.

REFERENCE 
PAGE

Rear air conditioning does not operate. 

1

P.55A-21

Rear air conditioning outlet air temperature does not increase. 
<vehicles with rear heater>

2

P.55A-29

Rear air conditioning outlet air temperature does not increase. 
<vehicles with rear cooler>

3

P.55A-38

Rear air conditioning outlet air temperature does not increase. 
<vehicles with rear A/C>

4

P.55A-52

Rear blower motor does not operate.

5

P.55A-69

Rear blower air amount cannot be changed.

6

P.55A-94

Air outlet vent cannot be changed with temperature. <vehicles 
with rear A/C>

7

P.55A-103

REAR AIR CONDITIONING DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-21

SYMPTOM PROCEDURES

INSPECTION PROCEDURE 1: Rear Air Conditioning does not Operate. <Vehicles with Rear Heater, 
Rear Cooler or Rear A/C>

AC309546

Power Supply Circuit

REAR AIR CONDITIONING DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-22

DIAGNOSIS

STEP 1. Check the front A/C operations.
Q: Do the front A/C work normally?

YES : Go to Step 2.
NO :  Refer to Manual A/C diagnosis Inspection procedure 

1 "When the ignition switch is "ON," the A/C does not 
operate 

P.55A-6

."

STEP 2. Check the rear blower motor operations.
Q: Do the rear blower motor work normally?

YES : Go to Step 3.
NO :  Refer to Manual diagnosis Inspection procedure 4 

"Blower fan and motor does not turn 

P.55A-12

."

AC204170

CONNECTORS : D-01, D-30

CZ

D-01

D-30

AC204173

CONNECTORS : D-208, D-210

BF

D-208

D-210

AC204176

CONNECTORS : E-01, E-09, E-20

BI

E-01, E-09,
E-20