GMC 1982 Light Duty Truck Service Manual page 141

1D-25 AIR CONDITIONING COMPRESSOR OVERHAUL
A - 6 C O M P R E S S O R L E A K
T E S T I N G ( E X T E R N A L A N D I N T E R N A L )
B ench-C heck Procedure
1. Install Test Plate J 9625 on R ear H ead of
com pressor.
2. A ttach center hose of M anifold Gage Set on
Charging Station to a refrigerant drum standing in an
upright position and open valve on drum .
3. Connect C harging Station high and low pressure
lines to corresponding fittings on Test Plate J 9625, using
J 5420 Gage A dapters if hoses are not equipped with valve
depressors.
• Suction port (low-side) of com pressor has large
internal opening. D ischarge port (hi-side) has sm aller
internal opening into compressor.
4. Open low pressure control, high pressure control and
refrigerant control on C harging Station to allow refrigerant
vapor to flow into compressor.
5. Using a Leak D etector, check for leaks at Pressure
Relief Valve, com pressor Shell to cylinder, com pressor front
head seal, and com pressor Shaft Seal. A fter checking, shut
off low pressure control and high pressure control on
Charging Station.
6. If an external leak is present, perform the necessary
corrective measures and recheck for leaks to make certain
the leak has been corrected.
7. Loosen the M anifold G age hose connections to the
Gage A dapters J 5420 connected to the low and high sides
and allow the vapor pressure to release from the compressor.
8. Disconnect both G age A dapters J 5420 from the Test
Plate J 9625.
9. R otate the com plete com pressor assembly (not the
crankshaft or drive plate hub) slowly several turns to
distribute oil to all cylinder and piston areas.
10. Install a shaft nut on the com pressor crankshaft if
the drive plate and clutch assembly are not installed.
11. Using a box-end w rench or socket and handle,
rotate the com pressor crankshaft or clutch drive plate on
the crankshaft several tu rn s to ensure piston assembly to
cylinder wall lubrication.
12. Connect the Charging Station high pressure line or
a high pressure gage and Gage A dapter J 5420 to the Test
Plate J 9625 high side connector.
13. A ttach an A dapter J 5420 to the suction or low
pressure port o f the Test Plate J 9625 to open the schrader-
type valve.
Oil will drain out of the com pressor suction port
adapter if the com pressor is positioned with the suction port
downward.
14. A ttach the compressor to the J 9396
F ix tu re. Clam p the com pressor Holding Fixture
vise so that the com pressor can be m anually turned with a
wrench.
15. Using a wrench, rotate the com pressor crankshaft
or drive plate hub 10-complete revolutions at a speed of
approxim ately one-revolution per second.
T urning the com pressor at less than one-revolution per
second can result in a lower pum p-up pressure and
disqualify a good pum ping compressor.
16. Observe the reading on H IG H pressure gage at the
com pletion o f the tenth revolution of the compressor. The
pressure reading for a good pumping com pressor should be
413.7 kPa (60 P.S.I.)
compressor. A pressure
344.75 kPa (50 p.s.i.) for the A-6 would indicate one or more
suction a n d /o r discharge valves leaking, an internal leak,
or an inoperative valve and the com pressor should be
disassembled and checked for cause of leak. Repair as
needed, reassemble and repeat the pum p-up test. Externally
leak test.
17. W hen the pressure pum p-up test is completed,
release the air pressure from the H IG H side and remove the
G age A dapters J 5420 and Test Plate J 9625.
18. Rem ove oil charge screw and drain the oil sump.
19. Allow the com pressor to drain for 10 minutes, then
charge with the proper am ount of oil. The oil may be poured
into the suction port.
If further assembly or processing is required, a shipping
plate or Test Plate J 9625 should be installed to keep out
air, dirt and m oisture until the com pressor is installed.
H olding
in a
or above for the A-6
reading of less than