Mitsubishi Montero (2004+). Manual — part 591

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-7

STEP 3. Check the A/C compressor clutch relay continuity.

Follow the table below to check the A/C compressor clutch
relay for continuity.

Q: Is the A/C compressor clutch relay in good condition?

YES : Go to Step 4.
NO : Replace the A/C compressor clutch relay. Then go to

Step 10.

STEP 4. Check the A/C compressor clutch operation.

Connect the positive battery terminal to the air conditioning
compressor clutch connector terminal 3 and ground the nega-
tive battery terminal to the body of the compressor.
Q: Can the sound of the A/C compressor clutch (click) be

heard?
YES : Go to Step 5.
NO : Replace the A/C compressor clutch. Then go to Step

10.

BATTERY VOLTAGE

TESTER
CONNECTION

SPECIFIED
CONDITION

Not applied

4

− 5

Open circuit

• Connect terminal 3 to the

positive battery terminal

• Connect terminal 1 to the

negative battery terminal

4

− 5

Less than 2
ohms

AC204715

3

1

4

5

AE

A/C
COMPRESSOR
CLUTCH RELAY

BATTERY

ACX01440AB

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-8

STEP 5. 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-146

).

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

switch are at operation pressure (ON) and the resistance is
less than two ohm between the respective terminals, then
the condition is normal. If open loop, replace the switch.

Q: Is the dual pressure switch operating properly?

YES : Go to Step 6.
NO : Replace the dual pressure switch. Then go to Step

10.

STEP 6. Check the A/C switch continuity.

Follow the table below to check the A/C switch for continuity.

Q: Is there continuity at the A/C switch?

YES : Go to Step 7.
NO : Replace the A/C switch. Then go to Step 10.

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

SWITCH
POSITION

TESTER
CONNECTION

SPECIFIED
CONDITION

Off

5

− 6

Open circuit

On

5

− 6

Less than 2 ohms

AC001370

OFF

ON

BLOWER
SWITCH
ASSEMBLY

AB

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-9

STEP 7. Check the blower switch continuity.

Follow the table below to check the blower switch for continuity.

Q: Is there continuity the blower switch?

YES : Go to Step 8.
NO : Replace the blower switch. Then go to Step 10.

STEP 8. 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 9.
NO : Replace the automatic compressor controller. Then

go to Step 10.

STEP 9. Measure the powertrain control module terminal
voltage.

Refer to GROUP 13A, Diagnosis

− Check at the Powertrain

Control Module (PCM)

P.13A-968

.

Q: Is the terminal voltage correct?

YES : Go to Step 10.
NO : Replace the PCM. Then go to Step 10.

STEP 10. Retest the system.
Q: Is the A/C operating properly?

YES : The procedure is 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

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-10

INSPECTION PROCEDURE 2: When the Air Outlet Changeover Control Knob is Moved to
DEFROSTER or DEFROSTER/FOOT Position, the A/C or the Inside/outside Air Changeover Damper
Motor does not Operate.

DIAGNOSIS

STEP 1. Check the defroster switch continuity.
Follow the table below to check the defroster switch for continu-
ity.

Q: Is the defroster switch in good condition?

YES : Go to Step 2.
NO : Replace defroster switch. Then go to Step 2.

STEP 2. Check each A/C part.
Q: Does A/C operate normally?

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 Inspection Procedure 1.

INSPECTION PROCEDURE 3: When the A/C is Operating, Temperature Inside the Passenger
Compartment does not Decrease (Cool Air is not Emitted).

DIAGNOSIS

STEP 1. Check for refrigerant leaks.
Q: Is the refrigerant leaking?

YES : Repair. Then go to Step 5.
NO : Go to Step 2.

AIR OUTLET
CHANGEOVER
CONTROL KNOB
POSITION

TESTER
CONNECTION

SPECIFIED
CONDITION

At the "DEFROSTER" or
"DEFROSTER/FOOT"
position

2

− 3

Less than 2 ohms

1

− 3

Open circuit

At the other positions

1

− 3

Less than 2 ohms

2

− 3

Open circuit

AC001398

HEATER
CONTROL
ASSEMBLY

AB