12
4. Air Purging
Air and moisture remaining in the refrigerant system
have undesirable effects as indicated below. There-
fore, 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 refriger-
ant 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.)
For GRF194MR5IAA, perform the air purge for tubes A
and B. For GRF244MR5IAA, perform the air purge for
tubes A, B, and C. 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
Hi
Lo
B
A
C
Service valve
on narrow
tube side
Service
valve on
wide tube
side
With push-pin
Hex wrench
(nominal size 4 mm, not provided)
Manifold gauge
(special for R410A)
Low-
pressure
valve
Open
Charging hose
(special for R410A)
Leave the
valve open.
Vacuum pump
adapter
(for preventing
reverse flow)
(special for
R410A)
Vacuum
pump
High-pressure valve
Fig. 20
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>
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
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.
●
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.
