GMC 4000 Series Service Manual page 86

white felt bag that is not attached to anything but
m erely rests on the baffle in the lower portion of
the receiver. As the refrigerant flows through an
opening in the lower portion of the receiver, it is
also filtered through a 100 mesh screen attached
to a baffle at the bottom of the receiver.
The desiccant in this assembly is to absorb
Subject
Periodic Service
Precautionary Service M e a s u r e s ................................................................
Performance Testing
Depressurizing the S y s t e m ...........................................................................
Evacuating the System
Charging the System
Adding Refrigerant (Small Amount)
Checking Compressor Oil Level and Adding O i l ....................................
Checking for L e a k s .........................................................................................
Replacing Compressor
Servicing Seals and Hoses
Condenser Assembly R e p la c e m e n t............................................................
Receiver-Dehydrator Assembly Replacement
Expansion Valve Replacement
Suction Throttling Valve Replacement
Evaporator and Heater Core Assembly R e p la ce m en t.........................
Collision Service
Blower Motor R e p la c e m e n t...........................................................................
PERIODIC SERVICE
(60 Days or 6000 Miles whichever occurs first)
1. Check front of condenser for an accumula­
tion of dirt, such as leaves, bugs, dirt, etc. Also
check to see that the space between the condenser
and radiador is also free of this material.
2. Inspect com pressor drive belt. Check and
adjust tension to 100 to 105 lbs. on belt tension
gauge. Adjust new belt tension to 120 to 130 lbs.
3. Operate system and check for correct oper­
ation in all control positions.
4. Check for refrigerant leaks and observe
refi-igerant passing through the sight glass with
system operating to see if there is any evidence of
bubbles (above 70°F. ambient).
PRECAUTIONARY SERVICE
MEASURES
Before any service is attempted which requires
the opening of refrigeration pipes or units, the
person doing the work should be thoroughly familiar
with "General Information" on refrigeration serv­
ice.
G M C S E R V I C E M A N U A L
any moisture that might be present in the system
after assembly. The screens trap any foreign ma­
terial which may enter the system during assembly.
These features of the assembly prevent obstruc­
tion to the valves or damage to the com pressor.
the proper inlet and outlet fitting connections.
ON-VEHICLE SERVICE
Contents of this Sub-Section are as follows:
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for safety and to prevent dirt and moisture from
getting into the system . Dirt contaminant is apt to
cause leaky valves or wear in the com pressor, and
moisture will freeze into ice at the expansion valve
and freeze the valve stem.
PRE -ASSEMBLY
dehydrated. They are to remain sealed until just
prior to making connections.
temperature before uncapping. (This prevents con­
densation of moisture from the air that enters into
the system.)
but the connections are not made, then the tubes
and other parts should not remain unsealed for
more than 15 minutes. Reseal connections if period
is to be longer. This applies particularly to par­
tially built-up system s that will be left overnight.
of Frigidaire-525 Viscosity Oil and charged with
a mixture of Refrigerant-12 and dry nitrogen to
AIR CONDITIONING
NOTE: Markings on top of the receiver show
Page No.
.......................................
The major reasons behind these measures are
1. All sub-assem blies are shipped, sealed and
2. All sub-assem blies should be at room
3. If, for any reason the caps are removed,
4. Compressors are shipped with 10 - 11 oz.
Sec. 1
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