GMC 1976 ZEO 6083 Maintenance Manual page 100

Figure 62-High Pressure Relief Valve Location
COMPRESSOR INTERNAL
MECHANISM
Service operations to the rear head or internal
mechanism of the compressor
should be performed
with the compressor removed from the vehicle
to insure
that the necessary degree of cleanliness may be main-
tained . Clean hands, clean tools and a clean bench,
preferably covered with clean paper, are of extreme
importance .
An inspection should be made of the internal
mechanism assembly to determine if any service
opeations should be performed. A detailed inspec
tion of parts should be made to determine if it is
economically feasible to replace them .
REMOVE
1 . Before proceeding with disassembly, wipe ex-
terior surface of compressor clean.
2. All oil in compressor should be drained and
measured . Assist draining by positioning compressor
with oil drain plug down .
Record the amount of oil
drained from the compressor .
3. Invert compressor and Holding Fixture J-9396
with front end of compressor shaft facing downward .
(figure 63) .
Additional oil may leak from compressor at this
time . All oil must be drained into a container so that
TOTAL amount can be measured . A liquid measur
ing cup may be used for this purpose. Drained oil
should then be discarded.
AIR CONDITIONING SYSTEM
1- 83
Figure 63-Compressor Installed in Holding Fixture
4. Remove four locknuts from threaded studs on
compressor shell and remove rear head . Tap uni-
formly around rear head if head is binding. (figure
63).
Wipe excess oil from all sealing surfaces on rear
head casting webs, and examine sealing surfaces (fig-
ure 64). If any damage is observed, the head should
be replaced .
Figure 64-Rear Head Removal