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Fig. 7-4
(3) Do a leak test of all joints of the tubing (both indoor
and outdoor) and all service valves. Bubbles indicate
a leak. Wipe off the soap with a clean cloth after a
leak test.
(4) After the system is found to be free of leaks, relieve
the nitrogen pressure by loosening the charge hose
connector at the nitrogen cylinder. When the system
pressure is reduced to normal, disconnect the hose
from the cylinder.
Evacuation
(1) Attach the charge hose end described in the preced-
ing steps to the vacuum pump to evacuate the tub-
ing and indoor unit. Confirm that the “Lo” knob of the
manifold valve is open. Then, run the vacuum pump.
The operation time for evacuation varies with the
tubing length and capacity of the pump. The follow-
ing table shows the amount of time for evacuation:
Manifold valve
Pressure
gauge
Lo Hi
Vacuum pump
Outdoor unit
Close
Open
Discharge
tube
Suction
tube
Liquid
tube
Close
Open
Balance
tube
Close
Open
Close
Open
Required time for evacuation
when 30 gal/h vacuum pump is used
If tubing length is If tubing length is
less than 49 ft. longer than 49 ft.
45 min. or more 90 min. or more
Evacuation is not necessary for the balance tube if
only 1 outdoor unit is installed.