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'tfall 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 R- 12 to the refrigeration system. Remember that every system has an exact quantity of R-12 with a tolerance of +5 grams than can be added. (Figure 5)
TO THE
R-12 CYLINDER
=REFRIGERATION SYSTEM
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)
FILLING OR | VALVE TO BE |
_ CHARGE TUBE | REFILLING |
OPENED WHEN |
TO THE | TO THE |
REFRIGERATION | CHARGE |
SYSTEM | CYLINDER |
TO THE | VALVE TO BE |
VACUUM | CLOSED |
PUMP | AFTER VACUUM |
Figure 6
In addition, check the graduated scale on the cylinder for the quantity of R-12 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-12 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 R-12 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-compresson 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 R-12 established for the system being charged. When the system is running, the suction pressure must be stabilized from 0.30 to 0.6 atmosphere.
