CUSTOM
AIR
CONDITIONING
1A-7
described,
remove low pressure
gauge
line at
P.O.A.
valve.
2.
Crack
open high (No. 2) and low (No. 1) pres-
sure
control valves on station, and allow refriger-
ant
gas to purge from system. Purge slowly enough
so that oil
does
not escape from system along with
refrigerant.
3.
When refrigerant flow nearly stops, connect low
pressure
gauge
line to
P.O.A.
valve.
4.
Turn
on vacuum pump and open vacuum control
valve (No. 3).
5
a
With
system purged as above, run pump until
26-28 inches of vacuum is obtained. Continue to run
pump for 15 minutes after the system reaches 26-28
inches vacuum.
NOTE:
In all evacuating procedures, the specifi-
cation of
26-28
inches of mercury vacuum is
used.
These
figures are
only
attainable
at or near sea
level.
For each 1000
feet
above
sea level where
this
operation is being performed, the specifica-
tions should be lowered by 1 inch. Example: at
5000 ft.
elevation,
only
21 to 23 inches vacuum can
normally
be
obtained.
6. If 26-28 inches vacuum (corrected to sea level)
cannot be obtained, close vacuum control valve
(No. 3) and shut off vacuum pump. Open refrigerant
control
valve (No. 4) and allow
some
refrigerant to
enter system. Locate and repair all leaks.
7. After evacuating for 15 minutes, add 1/2 pound
of refrigerant to system as described in
step
6
above. Purge this 1/2 pound and re-evacuate for 15
minutes.
This
second evacuation is to be certain that
as much contamination is removed from the system
as possible.
8.
Only
after evacuating as above, system is ready
for charging.
Note
reading on sight glass of charging
cylinder.
If it
does
not contain a sufficient amount
for a
full
charge,
fill
to the proper level.
9. Close low pressure valve on charging station.
Fully
open station refrigerant control valve (No. 4)
and
allow all liquid refrigerant to enter system.
When
full
charge of refrigerant has entered system
turn
off refrigerant control valve (No. 4) and close
both hand shut-off valves.
10. If
full
charge of refrigerant
will
not enter
system, close high pressure control and refrigerant
control
valves.
Start
engine and run at slow idle with
compressor operating.
Crack
refrigerant control
valve (No. 4) and low pressure control on station.
Watch
low side
gauge
and keep
gauge
below 50 psi
by regulating refrigerant control valve. Closing
valve
will
lower pressure.
This
is to prevent liquid
refrigerant
from reaching the compressor while the
compressor is operating. When required charge has
entered system, close refrigerant control valve and
close low pressure control.
11. System is now charged and should be perform-
ance tested before removing
gauges.
ADDING
REFR1GERANT-12
The
following procedure should be used in adding
small
amounts of refrigerant that may have been
lost by leaks, or while opening system for servicing
the compressor. Before adding refrigerant to re-
place that lost by leaks, check compressor oil level
and
add oil if necessary. See
ADDING
OIL.
NOTE:
This procedure will
only
apply
if the air
inlet
temperature
is
above
70°F.
at the condenser.
1. Remove caps from
P.O.A.
valve and compres-
sor
gauge
fittings. Attach
gauge
set to
gauge
fittings,
making
sure Schrader adapter J 5420 is between low
pressure
gauge
hose
and suction
gauge
fitting, and
J
6163 is between high pressure
gauge
hose
and
discharge
gauge
fitting.
2.
Start
engine,
turn
air conditioning temperature
control
knob to
full
cold position, blower control for
high speed A/C mode. Operate for ten minutes at
2000 rpm to stabilize system.
3.
Observe the refrigerant through the glass cover
of receiver-dehydrator with the system operating,
to see if there are any bubbles evident.
a.
If no bubbles are evident, then bleed system
slowly through the discharge valve until bubbles
appear
in the receiver-dehydrator. Add one pound
of refrigerant as explained under
CHARGING
THE
SYSTEM.
b.
If bubbles are visible in the receiver-
dehydrator
with the temperature control knob at
the
full
cold position and the blower at
"HF
;
speed,
it
indicates
partial
or complete plug in a line, or a
shortage of refrigerant, or both.
Correct
condi-
tion. Add refrigerant as explained below until the
sight glass clears, then add another one pound of
refrigerant.
4. Attach flexible
hose
from center fitting of
gauge
set loosely to refrigerant drum or on dis-
posable can valves. Open high and low pressure
valves on the
gauge
set slightly to purge pressure
gauge
lines of air. Tighten fitting of refrigerant
drum
or can, when satisfied that all air has been
removed from
gauge
lines. Close (clockwise) both
hand
shut-off valves of
gauge
set.
5.
Partially
charge system.
a.
Refrigerant-12
Drum
Method.
(1) Place
pail
containing hot water that
does
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