Panasonic U-72MF2U9 Installation Instructions Manual page 38

(3) Do a leak test of all joints of the tubing (both indoor
and outdoor) and all service valves. Bubbles indicate
a leak. Wipe off the soap with a clean cloth after a
leak test.
(4) 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.
Evacuation
(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. The operation time for evacuation
varies with the tubing length and capacity of the
pump.
Evacuation is not necessary for the balance tube if
only 1 outdoor unit is installed.
NOTE
The vacuum condition should be less than –14.7 psig
(–0.1 MPa) {–755 mmHg, 5 Torr}.
Manifold valve
Vacuum
Lo Hi
gauge
Open
Suction
tube
Open
Discharge
tube
Open
Liquid
tube
Open
Balance
tube
38
Vacuum pump
Close
Outdoor unit
Close
Close
Close