Armstrong Air 4SCU 16LS Series, Installation And Maintenance Instructions Manual

Page: 13 / 32

506859-01 Issue 1236 Page 13 of 32
3. Connect the vacuum pump (with vacuum gauge) to the
center port of the manifold gauge set.
4. Open both manifold valves and start vacuum pump.
5. Evacuate the line set and indoor unit to a minimum
of 500 microns or lower. During the early stages of
evacuation, it is desirable to close the manifold gauge
valve at least once to determine if there is a rapid rise in
pressure. A rapid rise in pressure indicates a relatively
large leak. If this occurs, the leak testing procedure
must be repeated.
6. When 500 microns or lower is maintained, close the
manifold gauge valves, turn off the vacuum pump, and
disconnect the manifold gauge center port hose from
the vacuum pump. Attach the manifold gauge center
port hose to a nitrogen cylinder with pressure regulator
set to 150 psig and purge the hose. Open the manifold
gauge valves to break the vacuum in the line set and
indoor unit. Close the manifold gauge valves.
7. Shut off the nitrogen cylinder and remove the manifold
gauge hose from the cylinder. Open the manifold gauge
valves to release the nitrogen from the line set and
indoor unit.
8. Reconnect the manifold gauge to the vacuum pump,
turn the pump on, and continue to evacuate the line set
and indoor unit until 500 microns is maintained within
a 20 minute period after shutting off the vacuum pump
and closing the manifold gauge valves.
9. When the requirements above have been met,
disconnect the manifold hose from the vacuum pump.
Open the service valves to break the vacuum in the line
set and indoor unit.