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TM 5-4120-355-14
(2) Evacuation.
(a) Connect hose assemblies of evacuation gage manifold to discharge valve access fitting and to the suction
access fitting of the unit, refer to figure 4-7.
(b) Connect vacuum pump to center hose of gage manifold.
(c) Evacuate pump down to 100 microns.
(d) Break vacuum by admitting refrigerant, subparagraph below.
CAUTION: Do not use the compound gage as an indicator for satisfactory vacuum pressure,
d. Charging the Refrigerant System. There are two preferred methods used to charge the refrigerant system.
NOTE: Whenever available, use recycled refrigerant for charging the refrigeration system.
(1) Sight glass method.
(a) Evacuate the system as described in c above.
(b) Remove cap from suction tube charging valve.
(c) Connect hose from refrigeration charging hookup loosely to suction tube charging valve. Open refrigerant drum
shutoff valve slightly to purge hose. Tighten connection at charging valve. Open shutoff valve and backseat charging valve.
(d) Refrigerant drum must be in upright position to allow only gaseous refrigerant to enter system.
(e) Start unit.
(f) To speed up charging, set refrigerant drum in warm water. Never use a heating torch for this purpose.
(9) Observe sight glass (fig. 4-13) at the time of charging, and even though the flash gas is apparent, shutoff
refrigerant flow and observe sight glass for a period of 10 to 20 minutes. If at the end of this period the sight glass is not free from
flash glass, admit a small amount of charge and observe for the same time period. Repeat this operation until sight glass is clear.
(h) Frontseat charging valves and close refrigerant drum shutoff valve. Stop the unit and disconnect manifold hoses
from charging valves, and install caps,
(2) Weight method. With this method, you are charging the unit with liquid.
(a) Evacuate the system as described above.
(b) Connect a bottle of refrigerant-22 to discharge high side access fitting, figure 4-7.
(c) Weigh refrigerant bottle.
(d) Invert charging cylinder and open valve on refrigerant bottle and allow refrigerant to flow through system.
(e) Periodically weigh bottle until it is Ighter by amount needed in system. This must be the exact amount.
CAUTION: Total amount of charge must be exactly 53 oz.
change 4 5-5

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