24 S4359128
CAUTION
8. Air Purging
Air and moisture remaining in the refrigerant system have
undesirable effects as indicated below. Therefore, they
must be purged completely.
●pressure in the system rises
●operating current rises
●cooling (or heating) efficiency drops
●moisture in the air may freeze and block capillary tubing
●water may lead to corrosion of parts in the refrigerant
system
■Air Purging with a Vacuum Pump (for Test Run)
(1) Check that each tube (both narrow and wide tubes)
between the indoor and outdoor units have been
properly connected and all wiring for the test run has
been completed.Note that both narrow and wide tube
service valves on the outdoor unit are kept closed at
this stage.
(2) Using an adjustable wrench or box wrench, remove
the valve caps from the service valve on both narrow
and wide tubes.
(3) Connect a vacuum pump and a manifold valve (with
pressure gauges) to the service port on the wide tube
service valve. (Fig. 8-1)
Be sure to 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.
(4) With the “Lo” knob of the manifold valve open, run the
vacuum pump. The operation time for the vacuum
pump varies with tubing length and the capacity of the
pump. The following table shows the amount of time
for evacuation:
Required time for evacuation when capacity
of 100 liter/h vacuum pump is used
If tubing length is If tubing length is
less than 33 ft. (10 m) more than 33 ft. (10 m)
10 min. or more 15 min. or more
The required time in the above table is calculated based on
the assumption that the ideal (or target) vacuum condition
is around 10 mmHg abs.
NOTE
HiLo
Indoor unit
Outdoor unit
Manifold valve
Pressure
gauge
Vacuum pump
1824_M_I
Fig. 8-1