4. 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 efficiency drops
moisture in the air may freeze and block capillary
water may lead to corrosion of parts in the
Air Purging with a Vacuum Pump
(for Test Run)
In order to protect the earth's environment, be sure to
use a vacuum pump to perform the air purge.
(Never perform an air purge by using the refrigerant
gas cylinder or other external gas, or by using the gas
inside the outdoor unit.)
Perform the air purge for tubes A and B. Use the same
procedures for all tubes.
In order to prevent charging errors with
A/C that uses R410A, the screw diameter
at the service valve charging port has
been changed. When recharging or per-
forming other servicing, use the special
charging hose and manifold gauge.
(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. 20).
Before using the vacuum pump
adapter, read the vacuum pump
adapter manual, and use the
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.
(nominal size 4mm,
Screw diameter: 1/2
UNF 20 threads
Cap nut tightening torque:
7 – 11 N·m
(70 – 110 kgf·cm)
(Tighten by hand, then use a
wrench to turn approximately 30 .)
<Structure of service valve on wide tube side>
When using a hex wrench to open the spindle, an
extremely small amount of refrigerant may leak.
This does not indicate a problem.
Use a hex wrench of a type to which force can be
(special for R410A)
(special for R410A)
Cap tightening torque:
20 – 25 N·m
(200 – 250 kgf·cm)
(Tighten by hand, then
use a wrench to turn.)