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Fig. 10-4
(3) Pressurize the system up to 4.15 MPa
(42 kgf/cm
2
G) with dry nitrogen gas and close the
cylinder 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 gas and liquid
service valves. Bubbles indicate a leak. Wipe
off the soap with a clean cloth after the 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.
10-2. Evacuation
Be sure to use a vacuum pump that includes a
function 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 gas 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
preceding 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
vacuum 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
Liquid
tube
Gas
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 pressurize the
system. Usually, the cylinder is
used in a vertical standing
position.
CAUTION
Use a cylinder specifically
designed for use with R410A.
07-115 SSHP_II 5/7/07 4:00 PM Page 102