58
GRFP
Fig. 8-4
(3) Pressurize the system up to 4.15 MPa (42
kgf/cm
2
G) with dry nitrogen gas and close the cylin-
der valve when the gauge reading reaches 4.15
MPa (42 kgf/cm
2
G). Then, test for leaks with liquid
soap.
(4) Do a leak test of all joints of the tubing (both
indoor and outdoor) and both wide and narrow
service valves. Bubbles indicate a leak. Wipe off
the soap with a clean cloth after a leak test.
(5) After the system is found to be free of leaks,
relieve the nitrogen pressure by loosening the
charge hose connector at the nitrogen cylinder.
When the system pressure is reduced to normal,
disconnect the hose from the cylinder.
8-2. Evacuation
Be sure to use a vacuum pump that includes a func-
tion for prevention of back-flow, in order to prevent
back-flow of pump oil into the unit tubing when the
pump is stopped.
●
Perform vacuuming of the indoor unit and tubing.
Connect the vacuum pump to the wide tube valve
and apply vacuum at a pressure of –755 mmHg (5
torr) or below.
Continue vacuum application for a minimum of 1
hour after the pressure reaches –755 mmHg.)
(1) Attach the charge hose end described in the pre-
ceding steps to the vacuum pump to evacuate the
tubing and indoor unit. Confirm that the “Lo” knob
of the manifold valve is open. Then, run the vacu-
um pump.
(2) When the desired vacuum is reached, close the
“Lo” knob of the manifold valve and turn off the
vacuum pump. Confirm that the gauge pressure is
under 667 Pa (–755 mmHg, 5 Torr) after 4 to 5
minutes of vacuum pump operation.
Manifold valve
Pressure
gauge
Lo
Hi
Vacuum pump
Outdoor unit
Narrow
tube
Wide
tube
Close
Close
Open
CAUTION
To avoid nitrogen entering
the refrigerant system in a
liquid state, the top of the
cylinder must be higher than
the bottom when you pres-
surize the system. Usually,
the cylinder is used in a ver-
tical standing position.
CAUTION
Use a cylinder specifically
designed for use with R410A.
04-393 DC INV Tech p 45-63 12/13/04 11:34 AM Page 58
