Leak Testing - Chevrolet 1991 Light Duty Truck Repair Manual

1B3-12 R-4 AIR CONDITIONING COMPRESSOR
K \ | Tighten
• Front head mounting screws to 27 N-m (20
ft.lbs.).
4. New shaft seal.
5. Clutch Rotor and Bearing, Clutch Coil and Pulley
Rim assembly to the front head using J 26271-A.
• Before fully seating the assembly onto the front
head, be sure the clutch coil terminals are in
the proper location in relation to the compres­
sor and that the three protrusions on the rear of
the clutch coil align with the locator holes in the
front head.
6. Clutch plate and hub assembly. Refer to "Clutch
Plate and Hub Assembly Replacement"earlier in
this section. Check to see that the clutch plate to
clutch rotor gap is 0.5-1.0mm (0.020-0.040 inches).
Tools Required:
J 9625-A Pressure Test Set
J 5420 Straight Fitting
J 25008-A Holding Fixture
J 23500-01 Portable Charging Station
1. Install J 9625-A on the rear head of the compres­
sor.
2. Attach the center hose of the manifold gage set on
the charging station to a refrigerant drum standing
in an upright position and open the valve on the
drum.
3. Connect the charging station high and low pres­
sure lines to corresponding fittings on J 9625-A,
using J 5420 if hoses are not equipped with valve
depressors.
• Suction port (low-side) of the compressor has a
large internal opening. The discharge port
(hi-side) has a smaller internal opening in to the
compressor.
4. Open the low-pressure control, high-pressure con­
trol and refrigerant control on the charging station
to allow refrigerant vapor to flow into the compres­
sor.
5. Using a leak detector, check for leaks at the pres­
sure relief valve, compressor shell to cylinder, com­
pressor front head seal, and compressor shaft
seal. After checking, shut off the low pressure con­
trol and high pressure control on the charging sta­
tion.
6. If an external leak is present, perform the neces­
sary corrective measures and recheck for leaks to
make certain the leak has been corrected.
7. Loosen the manifold gage hose connections to the
low and high sides and allow the vapor pressure to
release from the compressor.
8. Disconnect J 5420 from J 9625-A.
9. Rotate the complete compressor 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 compressor crankshaft if

LEAK TESTING

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 pis­
ton assembly to cylinder wall lubrication.
12. Connect the charging station high pressure line or
a high pressure gage and J 5420 to J 9625-A high
side connector.
13. Attach J 5420 to the suction or low pressure port
of J 9625-A to open the Schrader-type valve.
Oil will drain out of the compressor suction port
adapter if the compressor is positioned with the
suction port downward.
14. Attach the compressor to J 25008-A using metric
mounting screws. Clamp the compressor holding
fixture in a vise so that 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.
Turning the compressor at less than one-revolu­
tion per second can result in a lower pump-up
pressure and disqualify a good pumping compres­
sor.
16. Observe the reading on HIGH pressure gage at
the completion of the tenth revolution of the com­
pressor. The pressure reading for a good pumping
compressor should be 344.75 kPa (50 psi) or
above. A pressure reading of less than 310.275
kPa (45 psi) 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, reassembly and repeat
the pump-up test. Externally leak test.
17. When the pressure pump-up test is completed,
release the air pressure from the HIGH side and
remove J 5420 and J 9625-A.