Vacuuming - Hitachi mini-HNRQ1 Series Service Manual

3.6 Vacuuming

(1) Connect the pressure gauge and the charging hoses to the check joints of the stop valves with a vacuum
pump.
(2) Vacuum the refrigerant piping of the system with the vacuum pump until the pressure reaches -0.1MPa or
lower. Then, continue the vacuum pumping work for more than one hour.
(3) After that, turn off the vacuum pump and then observe the pressure for more than two hours.
(4) If the pressure is over than -0.1MPa obviously, a gas leak is suspected. Please check the leak position
and eliminate it. Then repeat the vacuuming work again.
CAUTION
!
● The vacuuming should be performed on the gas stop valve and the liquid stop valve simultaneously.
Otherwise, air may be left in the system and lead the system to be damaged.
● The tools are used for exclusive use of R410A.
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INSTALLATION