HEATER AND AIR CONDITIONING 1A-29
time as possible will be required to perform the
operation. Don't leave the system open any longer
than is necessary.
• Finally, after the operation has been completed and
the system sealed again, air and moisture should be
evacuated from the system before recharging.
GAUGE SET
The gauge set (fig. 41) is used when purging, evacua-
ting, charging or diagnosing trouble in the system. The
gauge at the left is known as the low pressure gauge.
The face is graduated into pounds of pressure and, in
the opposite direction, in inches of vacuum. This is the
gauge that should always be used in checking pressures
on the low pressure side of the system. When all parts of
the system are functioning properly the refrigerant
pressure on the low pressure side never fails below 0
pounds pressure. However, several abnormal conditions
can occur that will cause the low pressure to fall into a
partial vacuum. Therefore, a low pressure gauge is
required.
The high pressure gauge is used for checking pres-
sures on the high pressure side of the system.
The connection at the left is for attaching the low
pressure gauge line and the one at the right the high
pressure gauge line. The center connector is common to
both and is for the purpose of attaching a line for adding
refrigerant, discharging refrigerant, evacuating the sys-
tem and other uses. When not required, this line or
connection should be capped.
NOTE:
Gauge fitting connections should be in-
stalled hand tight only and the connections leak
tested before proceeding.
The hand shutoff valves on the gauge manifold do not
control the opening or closing off of pressure to the
gauges. They merely close each opening to the center
connector and to each other. During most diagnosing
and service operation, the valves must be closed. The
only occasion for opening both at the same time would be
to bypass refrigerant vapor from the high pressure to
the low pressure side of the system, or in evacuating
both sides of the system.
CHARGING STATION
The J-8393 Charging Station is a portable assembly of
a vacuum pump, refrigerant supply, gauges, valves, and
most important, a five (5) pound metering refrigerant
charging cylinder. The use of a charging ey'inder elim-
inates the need for scales, hot water pails, etc.
The chief advantage of this unit is savings. A very
definite savings in refrigerant and time can be obtained
by using this unit. Since the refrigerant is metered into
the system by volume, the correct amount may be added
to.
the system and charged to the customer. This, coupled
with the fact that the unit remains "plumbed" at all times
and thus eliminates loss of refrigerant in purging of
lines and hooking-up, combines to enable the operator to
get full use of all refrigerant purchased by the
dealership.
All evacuation and charging equipment is hooked to-
gether in a compact portable unit (fig. 42) which brings
air conditioning service down to the basic problem of
hooking on two hoses, and manipulating clearly labeled
valves.
Fig.
42—System Charging Station
This will tend to insure that the job will be done without
skipping operations. As a result, you can expect to save
time and get higher quality work, less chance of an over
or undercharge, or comeback.
The pump mount is such that the dealer may use his
own vacuum pump. The gauges and manifold are in com-
mon use. Thus a current air conditioning dealer can use
the equipment on hand and avoid duplication.
LEAK TESTING THE SYSTEM
Whenever a refrigerant leak is suspected in the system
or a service operation performed which results in dis-
turbing lines or connections, it is advisable to test for
leaks.
Common sense should be the governing factor in
performing any leak test, since the necessity and extent
of any such test will, in general, depend upon the nature
of the complaint and the type of service performed on
the system. It is better to test and be sure, if in doubt,
than to risk the possibility of having to do the job over
again.
NOTE:
The use of a leak detecting dye within
the system is not recommended because of the
following reasons:
1.
Refrigerant leakage can exist without any oil leakage.
In this case the dye will not indicate the leak, how-
ever, a torch detector will.
2.
The addition of additives, other than inhibitors, may
alter the stability of the refrigeration system and
cause malfunctions.
3.
Dye type leak detectors which are insoluble form a
curdle which can block the inlet screen of the ex-
pansion valve.
CHEVROLET CHASSIS SERVICE MANUAL
