Mitsubishi Montero (2002-2004). Manual - part 37

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-11

STEP 2. Check the dual pressure switch operation.
(1) Remove the dual pressure switch connector and connect 

the high/low pressure side terminals located on the harness 
side as shown in the illustration.

(2) Install a gauge manifold to the high-pressure side service 

valve of the refrigerant line. (Refer to 

P.55A-152

.)

(3) When the high/low pressure sides of the dual pressure 

switch are at operation pressure (ON) and there is 
continuity between the respective terminals.

Q: When the high/low pressure sides of the dual pressure 

switch are at operation pressure (ON), is there 
continuity between the respective terminals?
YES : Go to Step 3.
NO :  Replace the dual pressure switch. Then go to Step 5.

STEP 3. Measure the automatic compressor controller 
terminal voltage.
Refer to 

P.55A-18

.

Q: Is the automatic compressor controller terminal voltage 

correct?
YES : Go to Step 4.
NO :  Replace the automatic compressor controller. Then 

go to Step 5.

STEP 4. Measure the powertrain control module terminal 
voltage.
Refer to GROUP 13A, Diagnosis 

− Check at the Powertrain 

Control Module (PCM) 

P.13Ab-43

.

Q: Is the voltage correct?

YES : Go to Step 5.
NO :  Replace the PCM. Then go to Step 5.

STEP 5. Retest the system.
Q: Does the system produce cool air?

YES : The procedure complete. (If no malfunctions are not 

found in all steps, an intermittent malfunction is 
suspected. Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunction 

P.00-6

.)

NO :  Go to Step 1.

ITEM

OFF to ON

ON to OFF

Low-pressure side kPa 
(psi)

223 

± 27 (32.4 

± 3.9)

196 

± 20 (28.4 

± 2.9)

High-pressure side kPa 
(psi)

2,550 

± 200 

(369.9 

± 29)

3,140 

± 200 

(455.5 

± 29)

ACX00822

ON

OFF

196 ± 20
(284 ± 2.9)

223 ± 27
(32.4 ± 3.9)

2,550 ± 200
(369.9 ± 29)

3,140 ± 200
(455.5 ± 29)

kPa
(psi)

DUAL PRESSURE 
SWITCH

AF

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-12

INSPECTION PROCEDURE 4: Blower Fan and Motor does not turn.

DIAGNOSIS

STEP 1. Check the front blower relay continuity.
Follow the table below to check the front blower relay for conti-
nuity.

Q: Is the front blower relay continuity in good condition?

YES : Go to Step 2.
NO :  Replace the front blower relay. Then go to Step 5.

STEP 2. Check the blower motor operation.
When battery voltage is applied between the terminals, check 
that the motor operates.
Q: Is there any abnormal noise?

YES : Go to Step 3.
NO :  Replace the blower motor. Then go to Step 5.

BATTERY VOLTAGE

TESTER 
CONNECTION 

SPECIFIED 
CONDITION

Not applied

2 

− 5

Open circuit

• Connect terminal 3 

to the positive 
battery terminal

• Connect terminal 1 

to the negative 
battery terminal

2 

− 5

Less than 2 ohms

AC204714AB

FRONT BLOWER RELAY

AC001038 AB

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-13

STEP 3. Check the blower switch continuity.
Follow the table below to check the blower switch for continuity.

Q: Is there continuity at the blower switch?

YES : Go to Step 4.
NO :  Replace the blower switch. Then go to Step 5.

STEP 4. Check the resistor resistance value.
Use an ohmmeter to measure the resistance between the ter-
minals as indicated below. Check that the measured value is at 
the standard value.

Q: Is the measured value at the standard value?

YES : Go to Step 5.
NO :  Replace the resistor. Then go to Step 5.

STEP 5. Retest the system.
Q: Do the blower fan and motor operate?

YES : The procedure complete. (If no malfunctions are not 

found in all steps, an intermittent malfunction is 
suspected. Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunction 

P.00-6

.)

NO :  Go to Step 1.

SWITCH 
POSITION

TESTER 
CONNECTION 

SPECIFIED 
CONDITION

0 (OFF)

1 

− 3, 3 − 4, 3 − 5, 3 − 6 Open circuit

1 (LO)

3 

− 5

Less than 2 ohms

2 (ML)

1 

− 3

Less than 2 ohms

3 (MH)

3 

− 6

Less than 2 ohms

4 (HI)

3 

− 4

Less than 2 ohms

AC001371

BLOWER SWITCH
ASSEMBLY

AB

MEASUREMENT TERMINAL

STANDARD VALUE 

Ω

Between terminals 2 and 3 (LO) 2.79

Between terminals 1 and 2 (ML) 1.49

Between terminals 2 and 4 (MH) 0.36

AC002646

1 2

3 4

AB

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-14

INSPECTION PROCEDURE 5: Blower Fan and Motor does not Stop turning.

DIAGNOSIS

STEP 1. Check the harness wires between the blower 
motor connector D-113, the resistor connector D-115, and 
the blower switch connector D-101.
Q: Are the harness wires between the blower motor 

connector D-113, the resistor connector D-115, and the 
blower switch connector D-101 in good condition?
YES : Go to Step 2.
NO :  Repair the wiring harness. Then go to Step 4.

AC204170

CONNECTOR : D-101

BZ

HARNESS 
SIDE

1
4

2

3

5

6

AC204189

CONNECTORS : D-113, D-115

D-113

AB

D-115

D-113

HARNESS SIDE

HARNESS SIDE

D-115

1

2

1

2

3

4