GMC 4000 Series Service Manual page 98

dence of a major leak, indicating that little or no
oil has been lost from the system . (Minor leak in­
dicating very slow leakage.)
3. If oil drained in step 1 previously contains
any foreign material such as chips, or there is
evidence of moisture in the system , replace the
receiver-dehydrator assembly and flush all com­
ponent parts, or replace if necessary. After flush­
ing refrigeration system in this manner, the full
oil charge should be left in the new service com­
p ressor or 11 ozs., installed in an overhauled or
repaired com pressor.
COMPRESSOR REMOVAL
1. Connect the high and low pressure gauge
lines from the gauge set to the respective connec­
tions on the old com pressor on the vehicle. Be
sure valves on gauge set are fully clockwise to
close gauge set to center fitting, and that a J-5420
or J-9459 Schrader adapter is between low pressure
hose and suction gauge fitting, and also at the d is­
charge gauge fitting.
2. Remove the flare nut from center connec­
tion on gauge manifold or the plug in the gauge line
attached to the center connection. Wrap the line at
the outlet with a cloth to protect persons and ve­
hicle surfaces from oil or refrigerant.
3. Slowly depressurize refrigeration system
as instructed previously under "Depressurizing The
System."
4. While system is depressurizing, remove (if
desired) clutch assembly and coil from old com­
p ressor. If parts are not oil soaked and are in
good condition, lay them aside on a clean surface
as they may be installed on the new com pressor.
5. After the system is completely depressur­
ized, very slowly loosen screw which retains com ­
pressor fittings assembly to com pressor (see fig.
14). As screw is being loosened, work fittings a s­
sembly back and forth to break seal and carefully
bleed off any remaining pressure.
CAUTION: High pressure may still
exist at the discharge fitting. If this
pressure is released too rapidly there
will be a considerable discharge of re­
frigerant and oil.
6. When all pressure has been relieved, re­
move fittings assembly and O-ring seals.
7. Immediately cover com pressor openings.
A simple way is with a plate (sim ilar to the one on
new com pressor) which can be attached with fittings
assembly screw, using the O-rings to provide a
seal. See lower portion of figure 14.
8. Disconnect com pressor clutch coil wire and
remove com pressor mounting plates to bracket
bolts, front and rear.
G M C S E R V I C E M A N U A L
3 / 1 6 " TO 1 / 4 " STEEL ST O C K
from the com pressor got into the discharge line or
the condenser, all refrigeration system parts
should be cleaned and a new receiver-dehydrator
assembly should be installed.
ed in a clean dry container and replace com pressor
drain plug screw. Measure amount of oil drained.
See "Checking Compressor Oil Level and Adding
Oil" previously.
COMPRESSOR INSTALLATION
rotate com pressor shaft four or five tim es. This
perm its proper lubrication of compressor seal
over all its surface. Before compressor clutch is
mounted to the new com pressor, wipe the front
face of the com pressor thoroughly with a clean dry
cloth and, if necessary, clean front of compressor
with a solvent to remove any excess oil. Cleaning
com pressor in this manner will prevent any oil
AIR CONDITIONING
O -R IN G SEALS
V e -24 3 /4,;B F
X
IM P R O V IS E D C L O S U R E PLATE IN S T A L L E D
Figure 14— Compressor Fittings Installation
9. If there is any possibility that broken parts
10. Drain all oil from compressor just remov­
NOTE: Before installing a new com pressor,
Sec. 1
Page 91
J
: / 'L A I j
T
-3 3 1 3