Pontiac tempest 1968 Service Manual page 30

CUSTOM A I R C O N D I T I O N I N G
1A-3
COMPRESSOR
F i g . 1 A - 2 Schematic - Evacuating Refrigerant System
b. Remove caps from gauge fittings on P.O.A.
valve and compressor.
c. Attach Schrader valve adapter J 5420 to end
of hose from low pressure gauge and connect this
adapter fitted hose to suction gauge fitting.
d. Attach Schrader valve adapter J 6163 to end
of hose from high pressure gauge and connect this
adapter fitted hose to discharge gauge fitting.
3. Attach a flexible gauge hose to center fitting of
the gauge set and attach the other end of this hose
to the vacuum pump J 5428 or J 5428-01 (Fig. 1A-2).
4. The system can now be evacuated.
EVACUATING COMPLETE SYSTEM
1. Turn hand shut-off valve on low pressure gauge
of gauge set to full clockwise position.
2. Slowly turn valve on high pressure gauge coun­
terclockwise from full clockwise position, letting
any pressure build-up escape completely. Close high
pressure valve.
3. Check o i l level i n vacuum pump and add F r i g i -
daire 150 viscosity o i l or equivalent, If necessary,
to bring to proper level. Make sure dust cap on dis­
charge side of vacuum pump has been removed.
4. Start the vacuum pump and slowly open low and
high pressure sides of manifold gauge set to avoid
forcing o i l out of refrigeration system and the pump.
Pressure is now being reduced on both sides of
refrigeration system.
NOTE: If oil is blown from vacuum pump, it
should be refilled to the proper level with Frigi-
daire 150 viscosity oil or equivalent.
5. Observe low pressure gauge and operate vac­
uum
pump until gauge shows 2 6 - 2 8 " vacuum. Con­
tinue to run pump for ten additional minutes.
NOTE: In all evacuating procedures specification
of 26-28 inches of vacuum is used. This evacuation
can only be attained at or near sea level. For each
1000 feet above sea level where this operation is
being performed, specification should be lowered
by one inch of mercury vacuum. For example: at
5000 feet elevation only 21 to 23 inches of vacuum
can normally be obtained.
If vacuum cannot be pulled to the minimum spec­
ification for the respective altitude, i t indicates a
leak i n the system, gauge connections or a defective
vacuum pump. In this case, i t w i l l be necessary to