Page 20
IMPORTANT
Use a thermocouple or thermistor electronic vacuum
gauge that is calibrated in microns. Use an instrument
that reads from 50 microns to at least 10,000 microns.
1 − Connect manifold gauge set to the service valve ports :
low pressure gauge to
vapor
line service valve
high pressure gauge to
liquid
line service valve
2 − Connect micron gauge.
3 − Connect the vacuum pump (with vacuum gauge) to the
center port of the manifold gauge set.
4 − Open both manifold valves and start the vacuum
pump.
5 − Evacuate the line set and indoor unit to an
absolute
pressure
of 23,000 microns (29.01 inches of mercu-
ry). During the early stages of evacuation, it is desirable
to close the manifold gauge valve at least once to deter-
mine if there is a rapid rise in
absolute pressure
. A
rapid rise in pressure indicates a relatively large leak. If
this occurs, repeat the leak testing procedure.
NOTE The term
absolute pressure
means the total ac-
tual pressure within a given volume or system, above the
absolute zero of pressure. Absolute pressure in a vacuum
is equal to atmospheric pressure minus vacuum pressure.
6 − When the absolute pressure reaches 23,000 microns
(29.01 inches of mercury), close the manifold gauge
valves, turn off the vacuum pump and disconnect the
manifold gauge center port hose from vacuum pump.
Attach the manifold center port hose to a nitrogen cylin-
der with pressure regulator set to 150 psig (1034 kPa)
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.
CAUTION
Danger of Equipment Damage.
Avoid deep vacuum operation. Do not use compres-
sors to evacuate a system.
Extremely low vacuums can cause internal arcing
and compressor failure.
Damage caused by deep vacuum operation will void
warranty.
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 the absolute pressure does not rise
above 500 microns (29.9 inches of mercury) within a
20−minute period after shutting off the vacuum pump
and closing the manifold gauge valves.
9 − When the absolute pressure requirement above has
been met, disconnect the manifold hose from the vacu-
um pump and connect it to an upright cylinder of
HFC−410A refrigerant. Open the manifold gauge valves
to break the vacuum from 1 to 2 psig positive pressure in
the line set and indoor unit. Close manifold gauge valves
and shut off theHFC−410A cylinder and remove the
manifold gauge set.
