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AIR CONDITIONING
24-1 5
a. Loosen the test hose adapters at both the suc-
tion service port and the discharge service port.
b. Loosen the charging hose connection at the
gauge set manifold. This will purge air from the
charging hose. Tighten the connection as soon as the
air is purged.
c. Open the left gauge set manifold valve to purge
the air from the suction service test hose. Close the
valve and tighten the test hose adapter at the suction
service port.
d. Open the right gauge set manifold valve to
purge the air from the discharge test hose. Close the
valve and tighten the discharge test hose adapter at
the discharge service port.
(9) Operate the engine
at
1250 rpm with the vehi-
cle doors and windows open and the hood up.
(10) Push in the "Cool" button, and move the blow-
er switch to the number 2 position.
(11) If necessary, block the condenser to maintain
a discharge pressure of 225 to 250 psi. The system
must be charged through the evaporator suction serv-
ice port as follows:
a. Slowly open the suction service gauge valve. Me-
ter flow of refrigerant by adjusting the suction serv-
ice gauge valve
so
that the pressure registered at the
suction service gauge does not exceed
50
psi.
CAUTION: Keep the refrigerant container upright.
b. Add refrigerant gas until there is no foam visi-
ble at the sight glass. As soon as all foam clears, note
the weight registered on the refrigerant scale.
c. Watch the refrigerant weighing scale and add
exactly
Y 2
pound more refrigerant to the system.
Close the suction gauge valve.
NOTE: l o o
much refrigerant in the system can
cause abnormally high discharge pressures. Care
must
be
used so that exactly
1 / 2
pound of refriger-
ant is added after the foam clears in the sight glass.
d. Close the dispensing manifold valve. Remove
the test hoses and adapters from the service ports of
the compressor, and install the protective caps at the
service ports.
TEST 5
O V E R - A l l PERFORMANCE TEST
ing. This reduces the amount
of
heat the evaporator
can absorb from the air. In other words, high humid-
ity greatly reduces the evaporator's ability to lower
the temperature of the air delivered to the vehicle in-
terior.
Evaporator capacity used to reduce the amount of
moisture out of the air entering the vehicle adds ma-
terially to the comfort of the passengers. However,
an owner may expect too much from his air-condi-
tioning system on humid days. A performance
test
is
the best way to determine whether or not the system
is performing up to standard. This test also provides
valuable clues to the possible cause of trouble.
The preliminary inspections in TESTS 1 thru 4 out-
lined previously should be made before the "Over-All
Performance Test." Install the gauge set, as shown in
Figure 14.
NOTE: Air temperature in test room must
be
75OF
minimum for this test.
Performance Test
(AR-I, 2)
Start the engine and open the windows. The tem-
perature control lever must be in the
off
position.
Push in the "Cool" button and turn the blower
switch to position
NO.
2. The floor air doors and the
right and left side outlet cooler grilles should be fully
open and directed straight back.
Adjust engine speed to 1250 rpm. Arrange the
gauge set manifold hoses and tachometer leads to al-
low the hood to be lowered, and close the hood.
Place the Motor-Driven Psychrometer, Tool C-3704,
at the cowl inlet opening (Fig. 18). Distilled water
should be used with this meter to prevent drying out
and hardening the wet sock.
Place the Thermometer, Tool (2-3623, fully into the
right outlet grille opening. The left outlet should be
fully extended and directed towards the rear
of
the
vehicle.
Operate the air-conditioning system until a stabi-
lized condition on the gauges and thermometers has
been established. One of the most important steps in
Humidity (the amount of moisture in the air) has
an important bearing on the temperature of the air
delivered to the vehicle's interior. This is true of all
air-conditioned systems whether in the home, office
or vehicle. It is important to understand the effect
humidity has on the performance of the system.
When humidity is high, the evaporator has to perform
a double duty. It must lower the air temperature and
the temperature of the moisture carried in the air.
Condensing the moisture in the air, transfers a great
deal of heat energy into the evaporator fins and tub-
Fig. 18-Psychrometer
and
Thermometer ITypical)
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