Servicing Precautions - LG GR-349SQF.CEWQEHU Service Manual

SERVICING PRECAUTIONS

Air Recharging in Compressor
Test the refrigeration by connecting it electrically before
refilling operation. It is necessary to ascertain the function
of the motor-compressor and identify the defects
immediately. If defects have been found, empty the old
system of possible R134a residue by breaking off the end
of the extension piece at its narrow point. (Figure 1)
Replace the filter and any damaged components. Unsolder
and pull off the piece remaining inside the service tube and
then attach an complete extension with male Hansen and
at last, solder it to the same tube again. (Figure 2)
POINT TO BE
BROKEN
SERVICE TUBE EXTENSION
Figure 1
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 the heating of 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)
TO THE VACUUM
PUMP
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 30
minutes. (Figure 3)
In case that a considerable leakage occurs it will be
necessary to stop the vaccum pump and to add a small
quantity of Freon to the system, if vacuum should not be
obtained (pressure gauge can't fall to 1 atmosphere), start
the refrigeration unit and find the leakage with the special
leak-finder. When the defective soldering point is visible,
re-do it after opening the extension tube valve and
reestablishing the normal outside pressure inside the
group.
Because the melted alloy is sucked into the tubes and
block them, the pressure must be rebalanced when
vacuum is in the system in soldering. As soon as the
CHARGE TUBE
EXTENSION
FEMALE
HANSEN
MALE HANSEN
SOLDERING POINT
Figure 2
PRESSURE
GAUGE
Figure 3
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 that can be added. (Figure 4)
Before performing this operation (if the vacuum pump and
refilling cylinder are connected), make sure that the valve
placed between the vacuum pump and the refilling tube are
closed in order to keep the Freon for addition to the system.
(Figure 5)
FILLING OR
CHARGE TUBE
TO THE REFRIGERATION
SYSTEM
TO THE VACUUM PUMP
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 R-
134a 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
the motor-compressor. Therefore, proceed by adding the
original quantity of about 20-30 grams and close the valve
immediately.
The pressure rises and the motor compressor must start
sucking the gas and lowering the pressure again.
Regulate the valve again, in the safe way until reaching the
quantity of R134a established for the system being
charged. When the system is running, the suction pressure
must be stabilized between 0.30 to 0.6 atmosphere.
- 3 -
TO THE R134a CYLINDER
TO THE REFRIGERATION
SYSTEM
Figure 4
VALVE TO BE OPENED
WHEN REFILLING
TO THE CHARGE
CYLINDER
VALVE TO BE CLOSED
AFTER VACUUM
Figure 5