Chevrolet 30 Series 1967 Service Manual page 43

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.
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.
J-8393 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 cylinder 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.
F ig . 25 - Leak Detector
During most diagnosing
HEATER AND AIR CONDITIONING 1A-15
All evacuation and charging equipment is hooked to­
gether in a compact portable unit (fig. 24). It brings air
conditioning service down to the basic problem of hooking
on two hoses, and manipulating clearly labeled valves.
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.
Leak Detector
Tool J-6084 (fig. 25) is a propane gas-burning torch
which is used to locate a leak in any part of the system.
Refrigerant gas drawn into the sampling tube attached to
the torch will cause the torch flame to change color in
proportion to the size of the leak.
cylinders used with the torch are readily available
commercially throughout the country.
CAUTION: Do not use lighted detector in any
place where combustible or explosive gases,
dusts or vapors may be present.
Operating Detector
1. Open control valve only until a low hiss of gas is
heard, then light gas at opening in chimney.
2. Adjust flame until desired volume is obtained. This
is most satisfactory when blue flame is approxi­
mately 3/8" above reactor plate. The reaction plate
will quickly heat to a cherry red.
3. Explore for leaks by moving the end of the sampling
hose around possible leak points in the system. Do
not pinch or kink hose.
NOTE: Since R-12 is heavier than air, it is
good practice to place open end of sampling tube
immediately below point being tested, particu­
larly in cases of small leaks.
Propane gas fuel
CHEVROLET TRUCK SERVICE M ANUAL