Mitsubishi Montero (2002-2004). Manual — part 35

GENERAL DESCRIPTION

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HEATER, AIR CONDITIONING AND VENTILATION

55A-3

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GENERAL DESCRIPTION

M1551000100080

The heater system uses a two-way-flow full-air-mix
system that features high performance and low oper-
ating noise. The air conditioning (A/C) system is
basically the same as the conventional system, but a
new refrigerant system has been adopted as a
response to restrictions on the use of chlorofluoro-
carbons.

SAFETY PRECAUTIONS

WARNING

Wear safety goggles when servicing the
refrigeration system to prevent severe dam-
age to hands.

Because R134a refrigerant is a hydro fluorocarbon
(HFC) which contains hydrogen atoms in place of
chlorine atoms, it will not cause damage to the ozone
layer. Ozone filters out harmful radiation from the
sun. To assist in protecting the ozone layer,
Mitsubishi Motors Corporation recommends an
R134a refrigerant recycling device. Refrigerant
R134a is transparent and colorless in both the liquid
and vapor state. Since it has a boiling point of

− 29.8

°C(− 21.6 °F) at atmospheric pressure, it will be a

vapor at all normal temperatures and pressures. The
vapor is heavier than air, non-flammable, and non-
explosive. The following precautions must be
observed when handling R134a.

WARNING

Do not heat R134a above 40

°C (104°F) or it

may catch fire and explode.

R134a evaporates so rapidly at normal atmospheric
pressures and temperatures that it tends to freeze
anything it contacts. For this reason, extreme care
must be taken to prevent any liquid refrigerant from
contacting the skin and especially the eyes. Always
wear safety goggles when servicing the refrigeration
part of the A/C system. Keep a bottle of sterile min-
eral oil handy when working on the refrigeration sys-
tem.
1. Should any liquid refrigerant get into the eyes, use

a few drops of mineral oil to wash them out.
R134a is rapidly absorbed by the oil.

2. Next splash the eyes with plenty of cold water.
3. Call your doctor immediately even though irritation

has ceased after treatment.

CAUTION

Keep R134a containers upright when charging
the system.
In most instances, moderate heat is required to bring
the pressure of the refrigerant in its container above
the pressure of the system when charging or adding
refrigerant. A bucket or large pan of hot water not
over 40

°C (104 °F) is all the heat required for this

ITEMS

SPECIFICATIONS

Heater unit

Type

Two-way-flow full-air-mix system

Heater control assembly

Dial type

Compressor

Model

10S17C

Dual pressure switch
kPa (psi)

High-pressure switch ON to OFF: 3,140 (455.5), OFF to ON: 2,550(369.9)
Low-pressure switch ON to OFF: 196 (28.4), OFF to ON: 223 (32.4)

Refrigerant and
quantity g (oz)

Vehicles without rear
A/C or rear cooler

R134a (HFC-134a), Approximately 530

− 570 (18.7 − 20.1)

Vehicles with rear A/
C or rear cooler

R134a (HFC-134a), Approximately 730

− 770 (26.1 − 27.1)

GENERAL DESCRIPTION

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HEATER, AIR CONDITIONING AND VENTILATION

55A-4

purpose. Do not heat the refrigerant container with a
blow torch or any other means that would raise tem-
perature and pressure above this temperature. Do
not weld or steam clean on or near the system com-
ponents or refrigerant lines.

WARNING

The leak detector for R134a should be used
to check for refrigerant gas leaks.

CAUTION

Do not allow liquid refrigerant to touch bright
metal or it will be stained.
When metering R134a into the refrigeration system
keep the supply tank or cans in an upright position. If
the refrigerant container is on its side or upside
down, liquid refrigerant will enter the system and
damage the compressor. Refrigerant will tarnish
bright metal and chrome surfaces, and in combina-
tion with moisture can severely corrode all metal sur-
faces.

OPERATION

When the air conditioning is working under low loads
(e.g, in winter), the PCM controls the A/C compres-
sor, condenser fan and idle-up speed more effec-
tively, resulting in good fuel economy and quiet
engine operation. In addition, the condenser fan will
always run for five minutes as initial check after the
battery is reconnected.

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Condenser fan control
When operating the air conditioning switch

• When the signal which turns on the compressor

is output from the automatic compressor control-
ler, PCM activates the condenser fan relay and
rotates the condenser fan.

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Compressor control
When operating the air conditioning switch

• The automatic compressor controller stops the

compressor when the air thermo sensor detects a
temperature of 3.2

°C (38°F) or less. However, if

the ambient air temperature sensor detects a
temperature of 10

− 20°C (50 − 68°F), the con-

troller stops the compressor when the air thermo
sensor detects 6.2

°C (43°F) or less. Because of

this control, the compressor can work efficiently
when the air conditioning is under low load.

• The PCM stops the compressor when the engine

coolant temperature sensor detects 115

°C

(239

°F). In addition, the compressor stops for five

seconds when the accelerator position sensor
input exceeds 80%. Moreover, the compressor
stops during engine start and low engine speed.
Because of this control, the engine load can be
reduced.

• The dual pressure switch turns OFF when the

refrigerant pressure becomes excessively high or
low, thus protecting the compressor circuit. (See
Table below.)

• When these two sensors are all activated, the

dual pressure switch is ON, and the ignition
switch, blower switch, and air conditioning switch
are ON, the A/C compressor relay is energized.

• When operating the air outlet changeover control

knob

• When the air outlet changeover control knob is

moved to "DEFROSTER" or "DEFROSTER/
FOOT" position, the micro switch, which is con-
nected in series to the air conditioning switch, is
turned on. The other compressor control than the
above is the same as that when operating the air
conditioning switch.

MANUAL A/C DIAGNOSIS

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A/C Compressor Relay ON Conditions

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MANUAL A/C DIAGNOSIS

INTRODUCTION TO HEATER, AIR CONDITIONING AND VENTILATION DIAGNOSIS

M1552012200269

Air is drawn into the heater assembly from either the
outside, or from the inside of the passenger cabin if
DEFROST, maximum cooling or RECIRCULATION
are selected. The air is then forced through the evap-
orator where heat is removed, cooling and de-humid-
ifying the air. Depending on the temperature
selected, a portion of this air is then forced through
the heater core to achieve the selected discharge
temperature.

If the system does not cool properly, look for a prob-
lem with the refrigerant, blower or air distribution sys-
tems. If the system does not heat properly, look for a
problem with the coolant, blower or air distribution
systems fuses, circuit breaker and relays should be
checked

HEATER, AIR CONDITIONING AND VENTILATION DIAGNOSTIC TROUBLESHOOTING
STRATEGY

M1552009600289

Use these steps to troubleshoot heater and air condi-
tioning concerns. These diagnostic step are
designed to systematically check the systems and
components. Follow these steps carefully, and you
will be sure that you have exhausted most of the pos-
sible ways to find a heater, air conditioning and venti-
lation 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 that the malfunction is eliminated and the

system works properly.

Ignition switch (IG2)

ON

Remarks
(1) A/C compressor relay is de-energized
when any one switch, sensor or control
unit shown on the left turns off (HI).
(2) *: Automatic compressor controller
and PCM judges from input signals from
the sensors.

Blower switch

ON

Air conditioning switch or micro switch

ON

Air thermo sensor

*

Outside air temperature sensor

*

Engine coolant temperature sensor

*

Dual pressure switch

Low-pressure side 223 kPa
(32.4 psi) or higher

ON

High-pressure side 2,550
kPa (369.9 psi) or below

ON

A/C compressor relay driving transistor (within automatic
compressor controller and engine control module)

ON

MANUAL A/C DIAGNOSIS

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SYMPTOM CHART

M1552009900354

NOTE: For symptoms marked with an asterisk the
condenser fan might not operate when there is an air
conditioning low load from the air conditioning con-
denser control, so remove the battery terminal (

−

)

and then check the symptoms 5 minutes after initial
start control reconnection.

SYMPTOM PROCEDURES

INSPECTION PROCEDURE 1: When the Ignition Switch is "ON," the A/C does not Operate.

DIAGNOSIS

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

YES : Repair the leak. Then go to Step 10.
NO : Go to Step 2.

STEP 2. Check for excessive refrigerant.
Q: Is the refrigerant in good condition?

YES : Go to Step 3.
NO : Use the refrigerant recovery station to remove all of

the refrigerant, and then calculate the amount of the
refrigerant and charge it. Then go to Step 10.

SYMPTOM

INSPECTION
PROCEDURE

REFERENCE
PAGE

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

1

P.55A-6

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.

2

P.55A-10

When the A/C is operating, temperature inside the passenger
compartment does not decrease (cool air is not emitted).

3

P.55A-10

Blower fan and motor does not turn.

4

P.55A-12

Blower fan and motor does not stop turning.

5

P.55A-14

When the A/C is operating condenser fan does not turn.*

6

P.55A-16

Inside/Outside Air changeover is not possible.

7

P.55A-17