Mitsubishi Outlander (2013+). Manual - part 745

ON-VEHICLE SERVICE

HEATER, AIR CONDITIONER AND VENTILATION

55-36

REFRIGERANT GAS PRESSURE CHECK

CAUTION

• The temperature of equipment in the engine 

room is high and the refrigerant gas pressure 
is also high immediately after the engine and 
A/C operation are stopped, thus leave the 
vehicle for a while, and then perform the 
refrigerant gas pressure check.

• On completion, stop the engine and wait until 

the high-pressure side of the gauge manifold 
is depressurised. Then remove the quick 
joints and the others.

CAUTION

•

AC106028

A

AB

Sleeve

ACB03699

High-pressure
side service valve

Low-pressure
side service valve

AB

Place the quick joint onto the service valve, and 

press to fit the part A securely until the sleeve 
clicks into place.

•

AC106029

Low-pressure 
valve

Gauge manifold

Charging hose (red)

Quick joint 
(for high-
pressure)

Quick joint 
(for low-
pressure)

AB

Charging hose (blue)

High-
pressure valve

When connecting, run your hand along the 
hose while pressing to ensure that there are 
no bends in the hose.

1. Check that the engine and A/C are stopped.

2. Close the high-pressure valve of the gauge 

manifold.

3. Connect the charging hose (red) to the 

hi-pressure side of the gauge manifold.

4. Connect the quick joint (for high pressure) to the 

charging hose (red).

5. Install the quick joint (for high pressure) to the 

high-pressure side service valve of the vehicle.

6. Close the low-pressure valve of the gauge 

manifold.

7. Connect the charging hose (blue) to the 

low-pressure side of the gauge manifold.

8. Connect the quick joint (for low pressure) to the 

charging hose (blue).

9. Install the quick joint (for low pressure) to the 

low-pressure side service valve of the vehicle.

10.Start and fully warm up the engine, and then 

check that the engine speed of the test condition 
is satisfied.

11.Set the A/C control panel to the mode instructed 

in the test conditions.

12.Measure the high pressure/low pressure, and 

check that the measurement is within the 
permissible range of the table below. If the value 
is outside the permissible range, refer to the 
cooling performance check result, and perform a 
check according to the diagnosis chart of 
refrigerant system.

ON-VEHICLE SERVICE

HEATER, AIR CONDITIONER AND VENTILATION

55-37

NOTE: Prior to the measurement, wait until the 
refrigerant pressure is stable. (Approximately 10 
minutes after A/C operation start)

Garage ambient temperature 
°C

20

25

30

35

40

45

50

Compressor high pressure kPa 881 

−

1, 377

1, 086 

− 

1, 582

1,291 

− 

1,787

1,496 

− 

1,992

1,701 

− 

2,197

1,906 

− 

2,402

2,111 

− 

2,607

Compressor low pressure kPa

204 

− 

369

255 

− 

420

306 

− 

471

357 

− 

522

408 

− 

573

459 

− 

624

510 

− 

675

DIAGNOSIS BY REFRIGERANT 
PRESSURE

M1552023000225

A/C 
system 
symptom

Measurement circumstance

Cause

Measures

Hig
h 
pres
sure

Low 
pres
sure

Air 
outl
et 
tem
pera
ture

Note

Cooler is 
not 
effective.

Low High High

• Pressure for low 

pressure side is high, 
and high pressure 
side is low.

• When the A/C 

operation is stopped, 
the pressures of low 
pressure side and 
high pressure side 
immediately become 
identical.

• Leakage inside 

compressor

• Faulty 

compression of 
compressor

1. Check according to the 

compressor check.
1. When no foreign object 

is present to the oil, and 
when the colour is light 
grey, replace only the 
compressor.

2. When foreign objects 

are mixed to the oil, and 
the colour is black, 
replace the compressor 
and receiver.

2. Perform the evacuation 

sufficiently to remove the 
foreign objects and 
moisture in the cycle.

3. Fill the new gas to the 

specified amount.

High High High

• Low pressure 

side/high pressure 
side pressure is too 
high.

• Low pressure side 

piping is too hot to 
touch.

• Air is mixed to 

the refrigerant 
cycle.

• Evacuation is 

insufficient.

1. Perform the evacuation 

sufficiently, and remove 
the foreign objects and 
moisture in the cycle.

2. Fill the new gas to the 

specified amount.

ON-VEHICLE SERVICE

HEATER, AIR CONDITIONER AND VENTILATION

55-38

Sufficient 
cooling and 
insufficient 
cooling 
occur 
periodically.

Fluc
tuati
on

Fluc
tuati
on

Fluc
tuati
on

During the air 
conditioner operation, 
the low pressure side 
pressure alternates 
between the negative 
pressure and normal. 
(also in the high 
pressure side, the 
abnormal and normal 
statuses are alternated).

The moisture in 
the refrigerant 
cycle becomes 
frozen in the 
expansion valve, 
then the 
circulation of 
refrigerant is 
stopped 
temporarily. 
Subsequently, the 
status recovers to 
normal by the 
melting of ice.

1. Replace the receiver 

(drier).

2. Perform the evacuation 

sufficiently, and remove 
the moisture in the cycle.

3. Fill the new refrigerant to 

the specified amount.

Cooler is 
sometimes 
not 
effective. 
(works 
occasionall
y)

Low Vac

uum

Fluc
tuati
on

• The low pressure 

side pressure 
indicates the 
vacuum, and the high 
pressure side 
indicates the low 
pressure.

• To the piping before 

and after the 
expansion valve, 
frost or dew is 
observed.

• The foreign 

objects or 
moisture inside 
the refrigerant 
cycle deposits 
or 
freezes inside 
the expansion 
valve, and the 
refrigerant flow 
is disturbed.

• Because of the 

expansion 
valve operation 
failure, the 
refrigerant flow 
is disturbed.

1. Check the expansion 

valve.
1. If foreign objects are 

present inside the 
expansion valve, 
remove them by using 
an air gun or others.

2. When no foreign object 

is present, the 
expansion valve 
operation failure is 
suspected. Therefore, 
replace the expansion 
valve.

2. Perform the evacuation 

sufficiently, and remove 
the foreign objects and 
moisture in the cycle.

3. Fill the new refrigerant to 

the specified amount.

A/C 
system 
symptom

Measurement circumstance

Cause

Measures

Hig
h 
pres
sure

Low 
pres
sure

Air 
outl
et 
tem
pera
ture

Note

ON-VEHICLE SERVICE

HEATER, AIR CONDITIONER AND VENTILATION

55-39

Cooling 
effectivene
ss is bad.

Low Low Slig

htly 
high

• Low pressure 

side/high pressure 
side pressure is low.

• Outlet air 

temperature is high.

• Gas leakage is 

present to 
somewhere in 
the refrigerant 
cycle.

• Refrigerant gas 

amount is 
insufficient.

1. When the pressure gauge 

indication is close to zero, 
check the leak position, 
and then repair the 
leakage. Also, when the 
value is lower than the 
standard pressure, check if 
the gas leakage is present, 
and repair if necessary.

2. After checking the leak 

position, sufficiently 
perform the evacuation, 
then fill the new gas to the 
specified amount.

High High Slig

htly 
high

Low pressure side/high 
pressure side pressure 
is too high.

• Refrigerant 

amount is 
excessive.

• Condenser 

cooling is 
insufficient.

1. Clean the condenser fin 

(fouling, fin clogging)

2. Check the condenser fan 

motor (radiator fan) 
operation.

3. When 1 and 2 are normal, 

recover all the refrigerant. 
Then, perform a sufficient 
evacuation again, and fill 
the new gas to the 
specified amount.

High High High

• Low pressure 

side/high pressure 
side pressure is too 
high.

• Frost or dew is 

formed to the low 
pressure side.

Expansion valve 
trouble (valve 
opened 
excessively)

Replace the expansion valve.

Nor
mal

Nor
mal

Slig
htly 
high

-

Because of the 
slight difference of 
measurement 
environment, 
secular change of 
vehicle, or others, 
it is possible that 
the outlet 
temperature 
fluctuation has 
occurred.

Check the status for a while, 
and if the status does not 
improve, recover all the 
refrigerant, then fill to the 
appropriate amount.

A/C 
system 
symptom

Measurement circumstance

Cause

Measures

Hig
h 
pres
sure

Low 
pres
sure

Air 
outl
et 
tem
pera
ture

Note