Sears GR-151SPF - Manual (Page 4)

In case that a considerable leakage occurs and to stop the
vacuum pump will be necessary and 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
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)
Figure 5
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 for 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.
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.
-
6
-