44 S4179694
9. Air Purging
Air and moisture in the refrigerant system may have
undesirable effects as indicated below.
● pressure in the system rises
● operating current rises
● cooling (or heating) efficiency drops
● moisture in the refrigerant circuit may freeze and
block capillary tubing
● water may lead to corrosion of parts in the refriger-
ant system
Therefore, the indoor unit and tubing between the
indoor and outdoor unit must be leak tested and
evacuated to remove any noncondensables and
moisture from the system.
■ Air Purging with a Vacuum Pump (for Test Run)
Preparation
Check that each tube (both narrow and wide) between
the indoor and outdoor units have been properly
connected and all wiring for the test run has been
completed. Remove the valve caps from both the wide
and narrow service valves on the outdoor unit. Note
that both narrow and wide tube service valves on the
outdoor unit are kept closed at this stage.
Leak test
(1) With the service valves on the outdoor unit closed,
remove the 1/4 in. flare nut and its bonnet on the
wide tube service valve. (Save them for reuse.)
(2) Attach a manifold valve (with pressure gauges)
and dry nitrogen gas cylinder to this service port
with charge hoses.
Use a manifold valve for air
purging. If It is not available,
use a stop valve for this
purpose. The “Hi” knob of
the manifold valve must
always be kept closed.
(3)
Pressurize the system to no more than 150
P.S.I.G. with dry nitrogen gas and close the
cylinder valve when the gauge reading reaches
150 P.S.I.G. Then, test for leaks with liquid soap.
Cap
Narrow tube
Wide tube
Manifold valve
Pressure
gauge
Lo Hi
Nitrogen gas
cylinder
1370_C_I
Fig. 9-1
Fig. 9-2
Manifold valve
Pressure
gauge
Lo Hi
Charge hose
Outdoor unit
Service
valve
Wide tubeNarrow
tube
Indoor unit
Nitrogen gas cylinder
(In vertical standing
position)
1369_C_I
*
3-way valve is used for 3632 type.
*
CAUTION
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