LG GC-181SA.CSWQRAN, Service Manual

SERVICING PRECAUTIONS

-3-

If case that a considerable leakage occurs, it will be necessary
to stop the vacuum pump and add a small quantity of Freon to
the system, if vacuum should not be obtained (pressure gauge
doesn't fall to 1 atmosphere.) Start the refrigeration unit and
find the leakage with a special leak-finder. When the defective
soldering point is visible, repair it after opening the extension
tube valve and reestablishing the normal outside pressure
inside the system.
Because the melted solder is sucked into the tubes and blocks
them, the pressure must be rebalanced when vacuum is in the
system for soldering. As soon as the vacuum operation is over,
add the quantity (in grams) of R134a to the refrigeration
system. Remember that every system has an exact quantity of
R134a with a tolerance of ±5 grams than can be added. 
(Figure 5)

TO THE
R-134a CYLINDER

TO THE
REFRIGERATION
SYSTEM

FILLING OR
CHARGE TUBE

VALVE TO BE 
OPENED WHEN 
REFILLING

TO THE
REFRIGERATION
SYSTEM

TO THE 
CHARGE
CYLINDER

VALVE TO BE
CLOSED
AFTER VACUUM

TO THE

VACUUM

PUMP

TO THE

VACUUM

PUMP

PRESSURE

GAUGE

Before performing this operation (if the vacuum pump and
refilling cylinder are connected), make sure that the valve
placed between the vacuum pump and refilling tube are closed
to keep the Freon from adding to the system.(Figure 6)
In addition, check the graduated scale on the cylinder for the
quantity of R134a to be added; for example, if we have 750
grams of Freon in the cylinder and must add 165 grams to the
group, this amount will be reached when R134a has dropped to
585 grams, remembering that the indicator shows a lower limit
of meniscus. Do this after choosing the scale corresponding to
the gas pressure different scales reported as the same gas
pressure indicated by the pressure gauge on the top of the
column.
To make R134a flow into the system, open the valve placed at
the base of the cylinder and connected to the filling tube. The
amount of Freon cannot be added to the system all at once
because it may cause a blocking of motor-compressor.
Therefore, proceed by adding original quantity of about 20-30
grams and close the valve
immediately thereafter.
The pressure rises and the motor-compressor must start,
sucking the gas and making the pressure go down again.
Regulate the valve again, maintaining the same manner until
reaching the quantity of R134a established for the system being
charged. When the system is running, the suction pressure
must be stabilized from 0.10 to 0.4 atmosphere.

It is necessary to execute the soldering operation with valve
open so that the fumes caused by oil residue can come out
freely without blowholes between two tubes during heating the
point to be soldered.
The extension fitted with the male Hansen is connected to the
female fitting of the vacuum pump tube. (Figure 3) Air
evacuating from the system begins as soon as the pump starts.
The refrigeration system must be kept under vacuum until the
reading on the low-pressure gauge indicates vacuum (0
absolute, -1 atm., -760 mm hg.) In any case, it is advisable to
keep the pump running for about 60 minutes. (Figure 4)

Figure 3

Figure 4

Figure 5