GMC 1982 Light Duty Truck Service Manual page 53

1 B-10 AIR CONDITIONING
Overhead System
C-K Models
5 lbs.-4 oz.
5 lbs.
G Models
and safety plug from damage. It is good practice to replace
the cap after each use of the drum for the same reason.
If it is necessary to transport or carry any container of
R efrigerant-12 in a car, keep it in the luggage compartment.
If the drum is exposed to the radiant heat of the sun, the
resultant increase in pressure may cause the safety plug to
release or the drum to burst.
Welding or steam cleaning near any of the refrigerant
lines or components of the air conditioning system could
build up dangerous and damaging pressures in the system.
If the occasion arises to fill a small R efrigerant-12
drum from a large one, never fill the drum completely.
Space should always be allowed above the liquid for
expansion. If the R efrig erant-12 drum were completely full
and the temperature was increased, tremendous hydraulic
force could be developed.
H A N D L IN G OF REFRIGERANT LINES A N D
FITTINGS
Tighten all tubing connections as shown in torque chart
IB-7. Insufficient or excessive torque when tightening can
result in loose joints or deform ed joint part$. Either
condition can result in refrigerant leakage.
• All metal tubing lines should be free of dents or kinks to
prevent loss of system capacity due to line restriction.
• The flexible hose lines should never be bent to a radius
of less than 4 times the diameter of the hose.
• The flexible hose lines should never be allowed to come
within a distance of 63.5mm (2-1/2 in.) of the exhaust
manifold.
• Flexible hose lines should be inspected regularly for
leaks or brittleness and replaced with new lines if
deterioration or leaking is found.
• When disconnecting any fitting in the refrigeration
system, the system m ust first be discharged of all
r e f r ig e r a n t- 12. However, proceed very cautiously
regardless of gage readings. Open very slowly, keeping
face and hands away so that no injury can occur if there
happens to be liquid R efrigerant-12 in the line. If
Refrigerant Charge
C60 System
3 Lbs. - 12 ox.
3 lbs.
pressure is noticed when fitting is loosened, allow it to
bleed off as described under
A D D IN G OIL, E V A C U A T IN G A N D C H A R G I N G
P R O C E D U R E S FOR C.C.O .T. A /C S Y S T E M S .
• In the event any line is opened to atmosphere, it should
be immediately capped or taped to prevent entrance of
moisture and dirt, which can cause internal compressor
wear or plugged lines, condenser and evaporator core,
expansion tubes (orifice) or compressor inlet screens.
• The use of the proper wrenches when making
connections on " O " ring fittings is important. The use
of improper wrenches may dam age the connection. The
opposing fitting should always be backed up with a
wrench to prevent distortion of connecting lines or
components. W hen connecting the flexible hose
connections it is important that the swaged 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 fitting and damaging
the ground seat.
• " O " rings and seats must be in perfect condition. A
burr or piece of dirt may cause a refrigerant leak.
Always replace the " O " ring when a connection has
been broken. When replacing the " O " ring, first dip it in
clean 525 viscosity refrigeration oil.
• Where steel to aluminum connections are being made,
use torque for aluminum tubing (Refer to C h art 1B-
).
11
M A IN T A IN IN G CH EM IC A L STABILITY IN
THE REFRIGERATION SYSTEM
T he efficient operation of the air conditioning
refrigeration system is dependent upon the chemical
stability of the refrigeration system.
When foreign materials, such as dirt, air or moisture
contaminate the system, they will change the stability of
Refrigerant-12. They will also affect pressure-temperature
relationships, reduce efficient operation, possibly cause
interior corrosion and abnormal wear of moving parts.
The following general practices should be observed to
ensure chemical stability in the system:
1. Before disconnecting a refrigerant connection, wipe
away any dirt or oil at and near the connection to
reduce the possibility of dirt entering the system. Both
sides of the connection should be capped, plugged or
taped as soon as possible to prevent the entrance of dirt,
foreign material and moisture.
2. Keep tools clean and dry. This includes the manifold
Gage set and replacement parts.
3. When adding 525 viscosity refrigerant oil (Refer to
A D D I N G O IL in the D ischarging, Adding Oil,
Evacuating and Charging Procedures for C C O T A /C
Systems, the transfer device and container should be
clean and dry to assure that refrigeration oil remains as
moisture free as possible.
4. When it is necessary to "open" an A /C 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 A /C system open any
longer than is necessary.
5. Any time the A /C system has been "o pe n ed ," it
D I S C H A R G I N G ,