Komatsu 830E-AC Shop Manual page 934

ENVIRONMENTAL IMPACT OF AIR
CONDITIONING
Environmental studies have indicated a weakening of
the earth's protective Ozone (O
stratosphere. Chloro-flouro-carbon
(CFC's), such as R-12 refrigerant (Freon), commonly
used in mobile equipment air conditioning systems,
have been identified as a possible contributing factor
of the Ozone depletion.
Consequently, legislative bodies in more than 130
countries have mandated that the production and
distribution of R-12 refrigerant be discontinued after
1995. Therefore, a more "environmentally-friendly"
hydro-flouro-carbon.
(HFC) refrigerant, commonly identified as HFC-134a
or R-134a, is being used in most current mobile air
conditioning systems. Additionally, the practice of
releasing either refrigerant to the atmosphere during
the charging/recharging procedure is prohibited.
These restrictions require the use of equipment and
procedures which are significantly different from
those traditionally used in air conditioning service
techniques. The use of new equipment and tech-
niques allows for complete recovery of refrigerants,
which will not only help to protect the environment,
but through the "recycling" of the refrigerant will pre-
serve the physical supply, and help to reduce the
cost of the refrigerant.
AIR CONDITIONING FOR OFF-HIGHWAY
VEHICLES
Mining and construction vehicles have unique char-
acteristics of vibration, shock-loading, operator
changes, and climate conditions that present differ-
ent design and installation problems for air condition-
ing systems. Off-highway equipment, in general, is
unique enough that normal automotive or highway
truck engineering is not sufficient to provide the reli-
ability to endure the various work cycles encoun-
tered.
The cab tightness, insulation, and isolation from heat
sources is very important to the efficiency of the sys-
tem. It is advisable to close all vents, even the
intakes of pressurization systems, when there are
high humidity conditions.
N4-8
) layer in the outer
3
compounds
Operator Comfort
The general cleanliness of the system and compo-
nents is important. Dust or dirt collected in the con-
denser, evaporator, or air filters decreases the
system's cooling capacity.
The compressor, condenser, evaporator units, hoses
and fittings must be installed clean and tight and be
capable of withstanding the strain and abuse they
are subjected to on off-highway vehicles.
Equipment downtime costs are high enough to
encourage service areas to perform preventative
maintenance at regular intervals on vehicle Air Con-
ditioning (A/C) systems. (Cleaning, checking belt
tightness, and operation of electrical components).
PRINCIPLES OF REFRIGERATION
A brief review of the principles of air conditioning is
necessary to relate the function of the components,
the technique of troubleshooting and the corrective
action necessary to put the A/C unit into top operat-
ing efficiency.
Too frequently, the operator and the serviceman
overlook the primary fact that no A/C system will
function properly unless it is operated within a com-
pletely controlled cab environment. The circulation of
air must be a directed flow. The cab must be sealed
against seepage of ambient air. The cab interior must
be kept free of dust and dirt which, if picked up in the
air system, will clog the intake side of the evaporator
coil.
Air Conditioning
Air conditioning is a form of environmental control. As
applied to the cab, it refers to the control of tempera-
ture, humidity, cleanliness, and circulation of air. In
the broad sense, a heating unit is as much an air
conditioner as is a cooling unit. The term "air condi-
tioner" is commonly used to identify an air cooling
unit. To be consistent with common usage, the term
"air conditioner" will refer to the cooling unit utilizing
the principles of refrigeration; sometimes referred to
as the evaporator unit.
10/06 N04031