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. However, the A/C control panel has a
reduced number of buttons and a more compact
arrangement of necessary functions.

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 if irritation

decreases 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 pur-

pose. 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.

ITEM

SPECIFICATION

Heater unit

Type

Two-way-flow full-air-mix system

Heater control assembly

Push button type

Compressor

Model

10C17S

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)

R134a (HFC-134a), Approximately 730

− 770 (26.1 − 27.1)

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-4

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.

AUTO A/C DIAGNOSIS

INTRODUCTION

M1554006200028

After air is taken in through the damper, it is fed to
the evaporator by the blower fan and motor and
cooled. The air cooled by the air mix damper is
mixed appropriately with the warmed air to achieve a
comfortable temperature. If the A/C does not operate
or the cooled air is not discharged, the system com-
ponents or relay may be faulty.

AUTOMATIC AIR CONDITIONING TROUBLESHOOTING STRATEGY

M1554004700027

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.

AUTOMATIC AIR CONDITIONING TROUBLE
CODE DIAGNOSIS

M1554004800046

Retrieving full automatic air conditioning Diagnostic Trouble
Codes
Required Special Tool:

• MB991502: Scan Tool (MUT-II)

Content .. 75 76 77 78 ..