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JA
DESCRIPTION AND OPERATION
AIR CONDITIONING COMPONENTS
A/C PRESSURE TRANSDUCER
The switch is located on the discharge line near
the compressor. The pressure transducer functions as
the refrigerant system pressure sensor. It supports
the condenser/radiator fans and compressor func-
tions.
CLUTCH, PULLEY AND COIL
They are mounted on the compressor providing a
way to drive the compressor. The compressor clutch
and coil are the only serviced parts on the compres-
sor. When the compressor is not in operation, the
pulley free wheels on the clutch hub bearing. When
the coil is energized the clutch plate is magnetically
engaged with the pulley and turns the compressor
shaft.
COMPRESSOR
The compressor compresses the low pressure
refrigerant vapor from the evaporator into a high
pressure, high temperature vapor. The Scroll TRS-90
Compressor is used on all models. The system uses
polyalkylene glycol synthetic wax-free refrigerant oil
SP-15 PAG.
CONDENSER
It is located in front of the engine cooling radiator.
Its function is to cool the hot high pressure refriger-
ant gas. This causes it to condense into a high pres-
sure liquid refrigerant.
EVAPORATOR COIL
The coil removes heat and dehumidifies the air
before it enters the vehicle. The coil is located in the
A/C housing.
EVAPORATOR PROBE
The evaporator temperature probe prevents con-
densate water on the evaporator coil from freezing
and obstructing A/C system air flow. It does this by
cycling the compressor clutch on and off. The switch
is attached to the evaporator coil with the sensing
probe inserted into the coil fins.
EXPANSION VALVE
The valve is used to meter refrigerant into the
evaporator in accordance with cooling requirements.
The valve is located in front of the evaporator coil.
HIGH PRESSURE RELIEF VALVE
The valve is located at the rear of the compressor.
The valve is used to prevent excessive high system
HEATING AND AIR CONDITIONING
pressure. The valve vents the system when a pres-
sure of 3445-4135 kPa (500-600 psi) and above is
reached. This prevents damage to the compressor
and other system components. The valve closes with
a minimum pressure of 2756 kPa (400 psi).
FILTER/DRIER
The drier is used to remove any traces of moisture
from the refrigerant system. The filter is used to sep-
arate any foreign particles.
REFRIGERANT LINES
The lines are used to carry the refrigerant between
the various system components.
SERVICE GAUGE PORT
The high pressure gauge port is located on the
compressor discharge line. The low pressure gauge
port is located on the suction line.
THERMAL LIMITER SWITCH
The switch is used to measure compressor surface
temperature. If compressor surface temperature is
excessive the switch will cut battery feed voltage to
the compressor clutch. The switch will then reset
once compressor surface temperature returns to nor-
mal.
A/C PRESSURE TRANSDUCER
The A/C Pressure Transducer functions as the
refrigerant system pressure sensor. It supports the
condenser/radiator fans and compressor functions.
The pressure transducer is screwed attached to a
valve on the discharge line near the compressor.
A/C REFRIGERANT LINES
The air conditioning lines used on this vehicle are
made from reinforced rubber with a nylon liner on
the inner walls. The ends of the A/C lines are made
with light weight aluminum fittings or quick con-
nects.
The A/C lines use special connectors called quick
connects. There are four quick connects in the sys-
tem. Two are located at the condenser and the other
two are located at the expansion valve. Each quick
connector has a clip installed on it.
CAUTION: Never attempt to remove a clip or dis-
connect a quick connect without reclaiming all
refrigerant from the air conditioning system. The
system must be empty.
All quick connects use two O-rings to seal the con-
nection. The O-rings are made from a special type of
rubber that is not affected by R-134a refrigerant.
O-ring replacement is required whenever lines are
removed and installed. Use only O-rings specified for
24 - 3
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