Page 12
TO SUCTION
SERVICE VALVE
HFC-410A
GAUGE SET
NITROGEN
OUTDOOR UNIT
A Connect an HFC-410A manifold gauge set high pressure hose to the
suction valve service port.
B With both manifold valves closed, connect the cylinder of HFC-410A
refrigerant to the center port of the manifold gauge set.
C After the line set has been connected to both the indoor and outdoor
units, check the line set connections and indoor unit for leaks. Use the
following procedure to test for leaks:
A
B
NOTE - LATER IN THE PROCEDURE, THE HFC-410A CONTAINER WILL BE REPLACE BY THE
NITROGEN CONTAINER.
FIGURE 13
B-Evacuating the System
WARNING
Possible equipment damage. Avoid deep vacuum
operation. Do not use compressors to evacuate a
system. Extremely low vacuum can cause internal
arcing and compressor failure. Damage caused by deep
vacuum operation will void warranty.
IMPORTANT
Use a thermocouple or thermistor electronic vacuum
gauge that is calibrated in microns. Use an instrument
capable of accurately measuring down to 50 microns.
Evacuating the system of non-condensables is critical for
proper operation of the unit. Non-condensables are de-
ned as any gas that will not condense under tempera-
tures and pressures present during operation of an air
conditioning system. Non-condensables and water suc-
tion combine with refrigerant to produce substances that
corrode copper piping and compressor parts.
NOTE - Remove cores from service valves if not already
done.
1 - Connect an HFC-410A manifold gauge set as
illustrated in gure 14.
2 - Open both manifold valves and start the vacuum pump.
3 - Evacuate the line set and indoor unit to an absolute
pressure of 23,000 microns (29 inches of mercury).
NOTE - During the early stages of evacuation, it is desir-
able to close the manifold gauge valve at least once to
determine if there is a rapid rise in pressure this indicates
a relatively large leak. If this occurs, repeat the leak test-
ing 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.
4 - When the absolute pressure reaches 23,000
microns (29 inches of mercury), close the manifold
gauge valves, turn o the vacuum pump and
disconnect the manifold gauge center port hose from
vacuum pump. Attach the manifold center port hose
to a dry nitrogen cylinder 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.
5 - Shut o the dry nitrogen cylinder and remove the
manifold gauge hose from the cylinder. Open the
manifold gauge valves to release dry nitrogen from
the line set and indoor unit.
6 - Reconnect the manifold gauge to vacuum pump,
turn pump on, and continue to evacuate line set and
indoor unit until the absolute pressure does not rise
above 500 microns within a 20-minute period after
shutting o vacuum pump and closing the manifold
gauge valves.
7 - When the absolute pressure requirement above has
been met, disconnect the manifold hose from the
vacuum pump and connect it to an upright cylinder
of HFC-410A refrigerant. Open the manifold gauge
valve pressure line set to break vacuum with 2 to
5 psi.
8 - Perform the following:
A - Close manifold gauge valves
B - Shut o HFC-410A cylinder
C - Reinstall service valve cores by removing manifold
hose from service valve. Quickly install cores
with core tool while maintaining a positive system
pressure.
D - Replace the stem caps and secure nger tight, then
tighten an additional one-sixth (1/6) of a turn as
illustrated in gure 10.
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