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DESCRIPTION AND OPERATION (Continued)
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
this vehicle. Failure to use the correct type of O-ring
HEATING AND AIR CONDITIONING
will cause the connection to leak within a short
period of time.
When it is necessary to open the refrigeration sys-
tem, have everything needed to service the system
ready. The system should not be left open any longer
than necessary. Cap or plug all lines and fittings as
soon as they are opened. This will prevent the
entrance of dirt and moisture into the system. All
new lines and components should be capped or sealed
until they are ready to be used.
WARNING: AVOID BREATHING A/C REFRIGERANT
AND LUBRICANT VAPOR OR MIST. EXPOSURE MAY
IRRITATE EYES, NOSE AND THROAT. USE ONLY
APPROVED SERVICE EQUIPMENT MEETING SAE
REQUIREMENTS TO DISCHARGE R-134a SYSTEM.
IF ACCIDENTAL SYSTEM DISCHARGE OCCURS,
VENTILATE WORK AREA BEFORE RESUMING SER-
VICE.
R-134a SERVICE EQUIPMENT OR VEHICLE A/C
SYSTEM SHOULD NOT BE PRESSURE TESTED OR
LEAK TESTED WITH COMPRESSED AIR. SOME
MIXTURES OF AIR/R-134a HAVE BEEN SHOWN TO
BE COMBUSTIBLE AT ELEVATED PRESSURES.
THESE MIXTURES ARE POTENTIALLY DANGER-
OUS AND MAY RESULT IN FIRE OR EXPLOSION
CAUSING INJURY OR PROPERTY DAMAGE.
COMPRESSOR
The TRS90 is a fixed displacement type compressor
(Fig. 1).
CAUTION: Cleanliness
Clean the surfaces around the suction and dis-
charge ports of the compressor before opening the
system. If compressor is removed from vehicle,
apply tape to the opened ports to prevent any con-
tamination.
Fig. 1 TRS90 Compressor
24 - 3
is
extremely
important.
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