Allied Air Enterprises 4AC18LT - Manual (Page 12)

506469-01 Issue 1008
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.
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