GMC 1976 ZEO 6083 Maintenance Manual page 69

1- 5 2 AIR CONDITIONING SYSTEM
2. Cylinders or disposable cans should never be
subjected to high temperature when adding refriger-
ant to the system . In most instances, heating the
cylinder or can is required to raise the pressure in the
container higher than the pressure in the system dur-
ing the operation. It would be unwise to place the
cylinder on a gas stove, radiator or use a blow torch
while preparing for the charging operation, for a
serious accident can result . Remember, high pres-
sure means that great forces are being exerted against
the walls of the container. A bucket of warm water,
not over 125°F, or warm wet rags round the con-
tainer is all the heat that is required .
3. Do not weld or steam clean on or near the
system . Welding or steam cleaning can result in a
dangerous pressure buildup in the system .
4. Discharging large quantities of R-12 into a
room can usually be done safely as the vapor would
produce no ill effects; however, in the event of an
accidental rapid discharge of the system, it is recom-
mended that inhalation of large quantities of R-12 be
avoided. This caution is especially important if the
area contains a flame producing device such as a gas
heater . While R-12 normally is nonpoisonous, heavy
concentrations of it in contact with a live flame will
produce a toxic gas. The same gas will also attack all
bright metal surfaces .
5. Protection of the eyes is of vital importance!
When working around a refrigerating system, an ac-
cident may cause liquid refrigerant to hit the face. If
the eyes are protected with goggles or glasses, no
serious damage can result . Just remember, any R-12
liquid that touches you is at least 21 .7°F below zero .
If R-12 liquid should strike the eyes, here is what to
do :
A. Keep calm .
B. Do not rub the eyes . Splash the affected
area with quantities of cold water to gradually get the
temperature above the freezing point. The use of
mineral, cod liver or an antiseptic oil is important in
providing a protective film to reduce the possibility
of infection.
C. As soon as possible, call or consult an eye
specialist for immediate and future treatment.
PRECAUTIONS IN HANDLING
REFRIGERANT LINES
CAUTION :
The following precautions
should be observed when handling refriger-
ant lines:
1. All metal tubing lines should be free of kinks,
because of the restriction that kinks will offer to the
flow of refrigerant . The refrigeration capacity of the
entire system can be greatly reduced by a single kink .
2 . The flexible hose lines should never be bent to
a radius of less than 10 times the diameter of the
hose .
3 . The flexible hose lines should never be allowed
to come within a distance of 2-1/2" of the exhaust
manifold.
4. Flexible hose lines should be inspected at least
once a year for leaks or brittleness . If found brittle
or leaking they should be replaced with new lines.
5. Use only new lines that have been sealed dur-
ing storage .
6 . When disconnecting any fitting in the refriger-
ation system, the system must first be discharged of
all refrigerant . However, proceed very cautiously re
gardless of gauge readings . Open very slowly, keep-
ing face and hands away so that no injury can occur
if there happens to be liquid refrigerant in the line .
If pressure is noticed when fitting is loosened, allow
it to bleed off as described under "Purging the Sys-
tem" in this section .
WARNING : ALWAYS WEAR SAFETY GOG-
GLES WHEN OPENING REFRIGERANT LINES.
7. In the event any line is opened to atmosphere,
it should be immediately capped to prevent entrance
of moisture and dirt .
8 . The use of the proper wrenches when making
connections on "O" ring fittings is important. The
use of improper wrenches may damage the connec
tion . The opposing fitting should always be backed
up with a wrench to prevent distortion of connecting
lines or components . When connecting the flexible
hose connections it is important that the swagged
fitting and the flare nut, as well as the coupling to
which it is attached, be held at the same time using
three different wrenches to prevent turning the fit-
ting and damaging the ground seat .
9. "O" rings and seats must be in perfect condi-
tion . A burr or piece of dirt may cause a leak .
10 . Sealing beads on hose clamp connections
must be free of nicks and scratches to assure a perfect
seal .
MAINTAINING CHEMICAL
STABILITY IN THE
REFRIGERATION SYSTEM
The metal internal parts of the refrigeration sys-