Cadillac 60 Series 1963 Shop Manual page 408

HEATING AND AIR CONDITIONING
13-27
the system contains pure refrigerant 12 (plus a
certain amount of refrigeration oil which mixes
with the refrigerant), it is considered to be chem-
ically stable*
When foreign materials, such as dirt, air, or
moisture are allowed to get into the system, they
will change the pressure-temperature relationship
of the refrigerant. The system will no longer
operate at the proper pressures and temperatures,
and the efficiency of the system will decrease.
The following general practices should be ob-
served to insure chemical stability in the sys-
tem:
a. Leak Detector Fluid
Leak detector fluid (mixed with water per di-
rections on bottle) may be used by daubing or
squirting the liquid around joints to be tested.
Ordinary leaks will form a cluster of bubbles
almost immediately. Extremely small leaks will
form a white foam which will materialize with a
time limit from a few seconds to a minute, de-
pending on size of leak.
In order to locate leaks with this fluid, it is
essential that you see all of the surfaces you are
checking with a good light; otherwise, small leaks
could easily be overlooked.
1. Whenever it becomes necessary to discon-
nect a refrigerant connection, wipe away any dirt
or oil at or near the connection to eliminate the
possibility of dirt entering the system. Both sides
of the connection should be immediately capped
or plugged to prevent the entrance of dirt, mois-
ture or foreign material. All air contains mois-
ture. Air that enters any part of the system will
carry moisture with it and the exposed surfaces
will collect the moisture quickly.
2. Tools should be kept clean and dry. This
includes the Charging Station and the Gage Set.
3. When adding oil, the container and the trans-
fer tube through which the oil will flow should be
exceptionally clean and dry in order to keep the
refrigeration oil as moisture-free as possible.
For this reason, the oil container should not be
opened until ready for use, and should be capped
immediately after use.
4. When it is necessary to open a system, have
everything needed ready and handy so that as
little time as possible will be required to perform
the operation. Do not leave the system open any
longer than is necessary.
5. Any time the system has been opened and
sealed again, it must be properly evacuated, as
described in Note 21.
6. Use only refrigerant from a reputable deal-
er, as contaminated refrigerant will not only
lower the efficiency of the system, but will dam-
age the unit. Use only refrigerant 12 as refrig-
erant for the Cadillac system, since any other
refrigerant will damage the compressor or other
parts by incorrect pressure-temperature rela-
tionship.
17. Leak Detectors
There are two methods that may be used for
detecting leaks in the Air Conditioner system.
The use of a leak detector fluid or a torch type
leak detector is recommended.
b. Torch Type Leak Detector
Detecting a leak with the torch type detector is
accomplished by observing the color of the flame
in the head of the detector, when the sampling
tube is close to a refrigerant leak.
The flame can be described as three different
colors: green, blue, and purple. Green indicates
a small leak, blue indicates a medium leak, and
purple indicates a large leak.
CAUTION: Flames from detector are very
toxic and can cause severe damage to lungs if
inhaled. It is possible to create phosgene gas
if refrigerant comes in contact with metal heat-
ed to 800°F.
To operate unit, open valve until a low hiss of
gas is heard, then light the flame at opening in
detector chimney. Adjust flame until blue flame
is approximately 3/8" above reaction plate to
make detector as sensitive as possible for small
leaks.
When checking for leaks, always position sam-
pling tube below fitting or area to be tested, as
refrigerant 12 is a heavy vapor and will sink when
exposed to air.
It is best to test low pressure side of system
at drum pressure, which is much higher than
normal low side operating pressure.
In testing high pressure side for leaks, run
system for a few minutes to build up pressure in
high pressure side of system. Then stop engine
and test high pressure side of system for leaks.
18. Performance Test
To determine the efficiency of the Air Condi-
tioner system, run a performance test as outlined
below:
1. Open car windows and doors (except 75
series).