Pontiac FIREBIRD 1972 Service Manual page 108

CUSTOM AIR CONDITIONING 1 A-49
system, be sure that the pointer indicates to t i e center
of "0". Lightly tap gauge a few times to be sure
pointer is not sticking. If necessary, calibrate as fol-
lows:
a. Remove cover from gauge.
b. Holding gauge pointer adjusting screw firmly
with one hand, carefully force pointer in the
proper direction in proper amount to position
pointer through the center of "0" position. Tap
gauge a few times to be sure pointer is not stick-
ing. Replace gauge cover.
2. If gauge set is not already connected to P.O.A. valve
and compressor, connect as follows (Fig. 1A-47):
a. Close hand shut-off valves on gauge set by turn-
ing clockwise.
b. Remove caps from gauge fittings on P.O.A. valve
and compressor.
c. Attach valve adapter J 5420 to end of hose f r w
low pressure gauge and connect this adapter fitted
hose to suction gauge fitting.
d. Attach valve adapter J 9459 to end of hose from
high pressure gauge and connect this adapter fit-
ted 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
vacuum pump J 5428-03.
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 counter-
clockwise from full clockwise position, letting any
pressure build-up escape completely. Close high pres-
sure valve.
3. Check oil level in vacuum pump and, if necessary,
add refrigeration oil. 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 oil out of refrigeration system and pump.
Pressure is now being reduced on both sides of the
refrigeration system. NOTE: If oil is blown from
vacuum pump, it should be refilled to the proper
level.
5. Observe low pressure gauge and operate vacuum
COMPRESSOR
................................
................................
................................
................................
................................
................................
................................
................................
.................................
................................
................................
...............................
...............................
FROM RECEIVER
DEHYDRATOR
Fig. 1A-47 Schematic
-
Evacuating Refrigerant System