Ambient air passing through the condenser
removes the heat from refrigerant resulting
in physical state change in the refrigerant
from a gas to a liquid.
The liquid refrigerant moves on to the
receiver / drier where impurities such as
moisture and dirt are filtered out. The
receiver / drier also serves as the storage
tank for the liquid refrigerant. The liquid
refrigerant (still under high pressure) flows
to the expansion valve.
Since the refrigerant is colder than the air, it
absorbs the heat from the air and produces
cooled air, which is pushed into the cab by
the blower. The moisture in the air
condenses on the evaporator coil and drips
into the drain pan, which directs the water
out of the cab.
The refrigerant cycle is completed when the
heated low pressure gas is again drawn into
the compressor. The compressor cycles on
and off to maintain the desired cab
temperature. The Electronic De-icing
Thermostat is a micro controller based
module that measures evaporator coil
temperature and cycles the compressor
clutch to maintain a constant evaporator
pressure.
SAFETY EQUIPMENT
In servicing A/C and heater systems you will
be exposed to high pressures, temperatures
and several chemical hazards. Moving belts
and pulleys are normal shop hazards.
R-134a inside a canister or in an A/C system
is a liquid under pressure. When it escapes
or releases into the air, ITS TEMPERATURE
DROPS TO -5.8° C (21.6° F) “INSTANTLY”.
If it spills on your skin or in your eyes you
should flood the area with cool water and
SEEK MEDICAL ATTENTION FAST! It is a
good idea to wear gloves to prevent frost
bite if you should get refrigerant on your
hands.
NOTE: HFC R-134a refrigerant can be
dangerous if not properly handled. Liquid
R-134a may cause blindness if it contacts
the eyes and may cause serious frostbite if
it contacts the skin. Gaseous R-134a
becomes lethal (phosgene gas) when it
contacts open flame or very hot substances.
NEVER smoke when there is the possibility
of even small amounts of R-134a in the air.
Any servicing work that involves release or
addition of R-134a to the system must be
done by a competent refrigeration dealer
who has the proper equipment, knowledge,
and experience to service refrigeration
equipment.
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