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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
tubing
● water may lead to corrosion of parts in the
refrigerant system
■
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, B, C and D. Use the
same procedures for all tubes.
(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).
Fig. 20
Fig. 21
CAUTION
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.
CAUTION
CAUTION
Before using the vacuum pump
adapter, read the vacuum pump
adapter manual, and use the
adapter correctly.
In order to prevent charging errors with the
air conditioner that uses R410A, the screw
diameter at the service valve charging port
has been changed.When recharging or
performing other servicing, use the special
charging hose and manifold gauge.
● 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
easily applied.
Service
valve on
wide tube
side
Service
valve on
narrow
tube side
A
B
C
D
Vacuum
pump
Vacuum pump
adapter
(for preventing
reverse flow)
(special for
R410A)
High-pressure valve
Manifold gauge
(special for R410A)
Low-pressure
valve
Leave the
valve open.
Open
Charging hose
(special for R410A)
Hex wrench
(nominal size 4mm,
not provided)
With push-pin
HiLo
Cap tightening torque:
20 – 25 N·m
(200 – 250 kgf·cm)
(Tighten by hand, then
use a wrench to turn.)
Stopper
Spindle
Screw diameter: 1/2
UNF 20 threads
Valve core
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>
08-253 CMRV3146EH_OU EN 10/14/08 2:39 PM Page 16