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S4359146
11. 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 the tubing between the
indoor and outdoor units
must be checked for leaks
and
evacuated to remove
air and moisture.
■ Air Purging with a Vacuum Pump (for Test Run)
Preparation
Check that each tube (both narrow and wide) between
the indoor and outdoor units has been properly con-
nected and all wiring for the test run has been com-
pleted. 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 the flare
nut and its bonnet for reuse.)
(2) Attach the nitrogen gas cylinder to the service
port of the wide tube via a manifold valve with
pressure gauges. (See Fig. 11-2)
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 about 150 P.S.I.G. with
dry nitrogen gas and close the cylinder valve when
the gauge reading reaches about 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
Manifold valve
Pressure
gauge
Lo Hi
Charge hose
Outdoor unit
Service
valve
Wide tubeNarrow
tube
Indoor unit
Nitrogen gas cylinder
(In vertical standing
position)
2090_C_I
*
3-way valve is used for 3642 type.
*
Fig. 11-1
Fig. 11-2
CAUTION