Komatsu 830E-AC Shop Manual page 948

If an incorrect charge is suspected, recover the
refrigerant from the system, and charge the system
with the correct operating weight 3.4 kg (7.4 lb). This
is not only the recommended procedure, but it is also
the best way to ensure that the system is operating
with the proper charge and providing optimum cool-
ing. Using the sight glass to determine the charge
is not an accurate method.
An unclear sight glass on R-134a systems can
indicate that the system may be low on refriger-
ant. However, the sight glass should not be used
as a gauge for charging the system. Charging the
system must be done with a scale to ensure the
proper amount of refrigerant has been added.
R-134a Refrigerant Containers
Two basic, readily available containers are used to
store R-134a: the 14 or 28 kg (30 or 60 lb) bulk canis-
ters (Figure 4-12).
Always read the container label to verify the contents
are correct for the system being serviced. Note the
containers for R-134a are painted light blue.
FIGURE 4-12. R-134a CONTAINERS
1. 14 kg (30 lb)
Cylinder
N4-22
2. 28 kg (60 lb)
Cylinder
Operator Comfort
SYSTEM LEAK TESTING
Refrigerant leaks are probably the most common
cause of air conditioning problems, resulting from
improper or no cooling, to major internal component
damage. Leaks most commonly develop in two or
three places. The first is around the compressor shaft
seal, often accompanied by an indication of fresh
refrigerant oil. If a system is not operated for a while
(winter months), the shaft seal may dry out and leak
slightly. The centrifugal force of the clutch pulley
spinning can also cause the problem. When the sys-
tem is operated and lubricant wets the seal, the leak
may stop. Such leaks can often be located visually,
or by feeling with your fingers around the shaft for
traces of oil. (The R-134a itself is invisible, odorless,
and leaves no trace when it leaks, but has a great
affinity for refrigerant oil.)
A second common place for leaks is the nylon and
rubber hoses where they are crimped or clamped to
the fittings, or where routing allows abrasion. Other
threaded joints or areas where gaskets are used
should be visually and physically examined. Moving
your fingers along the bottom of the condenser and
evaporator, particularly near the drain hole for the
condensate will quickly indicate the condition of the
evaporator. Any trace of fresh oil here is a clear indi-
cation of a leak.
Usually, a 50% charged system is enough to find
most leaks. If the system is empty, connect the mani-
fold gauge set to the system and charge at least 1.6
kg (3.5 lbs) of refrigerant into the system.
Use extreme caution when leak testing a system
while the engine is running.
In its natural state, refrigerant is a harmless, col-
orless gas, but when combined with an open
flame, it will generate toxic fumes (phosgene
gas), which can cause serious injuries or death.
NOTE: The refrigerant is heavier than air and will
move downward when it leaks. Apply pickup hose or
test probe on the under-surface of all components to
locate leaks.
10/06 N04031