Chevrolet 1977 10 Series, Repair Manual, Page: 39 / 468

AIR CONDITIONING
1B-33
COMPRESSOR LEAK TESTING - EXTERNAL AND INTERNAL
A-6 and R-4 Compressors
Bench-Check Procedure
1. Install Test Plate J-9625 on rear head of compressor.
2. A ttach center hose of gage manifold set on Charging
Station to a refrigerant drum standing in an upright position
and open valve on drum.
3. Connect Charging Station H IG H and LOW pressure
lines to corresponding fittings on Test Plate J-9625, using
J-5420 Gage Adapters.
NOTE:
Suction port of com pressor has large internal
opening. Discharge port has small internal opening
into compressor.
4. Open LOW pressure control, H IG H pressure
control and R E F R IG E R A N T control on Charging Station
to allow refrigerant vapor to flow into compressor.
5. Using Leak Detector, check for leaks at pressure
relief valve, compressor shell to cylinder, compressor front
head seal (and also rear head seal and oil charge port on
A-6 compressor), and com pressor shaft seal. A fter checking,
shut off LOW pressure control and H IG H 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 manifold gage hose connections to the
Gage A dapters J-5420 connected to the LOW and H IG H
sides and allow the vapor pressure to release from the
compressor.
8. Disconnect both Gage A dapters J-5420 from the
Test Plate J-9625.
9. R otate the complete 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 wrench or socket and handle,
rotate the compressor crankshaft or clutch drive plate on
the crankshaft several turns to ensure piston assembly to
cylinder wall lubrication.
12. Connect the Charging Station H IG H pressure line
or a H IG H pressure gage and Gage A dapter J-5420 to the
Test Plate J-9625 H IG H side connector.
13. A ttach a A dapter J-5420 to the suction or LOW
pressure port of the Test Plate J-9625 to open the schrader-
type valve.
NOTE:
Oil will drain out of the compressor suction
port adapter if the com pressor is positioned with the
suction port down.
14. A ttach the com pressor to the Holding Fixture J-
25008-1, (R-4 compressor) and J-9396 (A-6 compressor),
and clamp the fixture in a vise so th at the compressor can
be manually turned with a wrench.
15. Using a wrench, rotate the compressor crankshaft
or drive plate hub 10 complete revolutions at a speed of
approximately one revolution per second.
NOTE:
Turning 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 the H IG H pressure gage
at the completion of the tenth revolution of the compressor.
The pressure reading for a good pum ping compressor
should be 50 p.s.i. or above for the R-4 and 60 p.s.i. or above
for the A-6 compressor.
A pressure reading of less
than 45 p.s.i. for the R-4 or 50 p.s.i. for the A-6
would indicate one or more suction and/or
discharge valves leaking, an internal leak, or an
inoperative valve and the compressor 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
Gage A dapters J-5420 and Test Plate J-9625.
18. On the R-4, tilt the com pressor so that the
compressor suction and discharge ports are down. D rain the
oil from the compressor.
On the A-6, remove 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.
NOTE:
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.