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24-1
2
AIR CONDITIONING
a passage between the discharge pressure gauge and
the center manifold outlet.
The detailed instructions for the proper use of the
gauge set manifold are contained in the test covering
each test and service operation employing these
gauges.
TEST 1
TEST SYSTEM PRESSURE
(Engine not Running)
Install the gauge set manifold. For identification of
the test hose connections at service ports see Figure
14.
After tightening the service port adapters, make
sure
that the needle valve located below the discharge
pressure gauge is open. Purge air from the gauge
hoses (Fig. 15) as follows:
(1) Open the suction gauge valve momentarily, then
close it.
(2) Open the discharge gauge valve momentarily,
then close
it.
(3) Loosen the compressor inlet suction hose con-
nection at the manifold momentarily, then tighten it.
If the vehicle has been parked and the system was
not operating, the gauge pressure should be normal
for temperature of the system. Refer to the "Temper-
ature-Pressure Relationship Chart."
If no pressure is indicated on the gauges it means
that the system is empty, due to a leak. It will
be
nec-
essary to evacuate, charge with a sweep-test charge,
locate and correct the leak, purge the test charge, re-
place the drier, vacuum the system and charge the
system with the proper amount of refrigerant 12.
If pressures are normal, proceed with the next test
and adjustment.
TEST 2
REFRIGERANT LEVEL
The system must be operated at high blower speed,
when this test is made, and when adding to the charge
with vehicle doors and windows open.
The sight glass
is
an integral part of the receiver-
strainer-drier. The outlet line (liquid) from the con-
denser must be attached to the connection marked
IN. The word IN is stamped on the top face of the in-
let connection (Fig. 16). If the receiver-strainerdrier
is reversed and the lines are connected wrong, the
system must be purged, the lines reversed and the
system recharged.
Block the air flow across the condenser to raise the
discharge pressure to 225 to 250 psi, and check the
sight glass for foam. There should be no foam. If
sight glass is clear, remove the air restriction from
the condenser and allow the discharge pressure to re-
turn to normal.
If the foam shows in the sight glass when the dis-
charge pressure is 225 to 250 psi,
it
indicates the sys-
63x1
05
Fig.
I
&Sight
Glass
tem is low on refrigerant. The proper amount of
re-
frigerant required to complete a full charge may be
added to the system as follows: Maintaining the dis-
charge pressure at 225 to 250 psi, add refrigerant gas
through the suction side of the system until foam is
cleared from sight glass, then add exactly one-half
(Y2)
pound of refrigerant.
TEST 3
TESTING THE SYSTEM FOR LEAKS
The Leak Detector Torch Tool C-3569 is a propane
gas-burning torch used to locate a leak in any part of
the refrigeration system. Refrigerant gas drawn into
the sampling
or
"snifter" tube will cause the flame to
change color in proportion to the size of the leak. A
very small leak will produce a flame varying from
yellowish-green to bright green. A large leak will pro-
duce a brilliant blue flame.
CAUTION: Do not use the lighted detector in any
place where explosive gases, dust or vapors are
present. Do not breathe the fumes that are pro-
duced by the burning of refrigerant gas. Large con-
centrations of refrigerant in the presence of a live
flame become dangerously toxic.
Observe the flame through the window of the burn-
er shield, not through the top of the shield.
If the flame remains bright yellow when the tester
is removed from the possible leak point, insufficient
air is being drawn in through the sampling tube, or
the reaction plate is dirty.
(1) Open the torch valve until you hear a faint hiss
of escaping gas. Light the test torch and adjust the
valve until the flame
is
very small. A small flame will
detect large as well as small leaks, whereas a large
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