Midea MCH2U-18PHH2 Service Manual page 13

Procedure
1). Confirm that both the 2-way and 3-way
valves are set to the opened position
Remove the valve stem caps and confirm that
the valve stems are in the opened position.
Be sure to use a hexagonal wrench to operate
the valve stems.
2). Connect the charge hose with the push pin
of handle lo to the 3-way valves gas service
port.
3). Air purging of the charge hose.
Open the handle Lo valve of the manifold
valve slightly to purge air from the charge
hose for 5 seconds and then close it quickly.
4). Set the 2-way valve to the close position.
5). Operate the air conditioner at the cooling
cycle and stop it when the gauge indicates
0.1MPa.
6). Set the 3-way valve to the closed position
immediately
Do this quickly so that the gauge ends up
indicating 0.3 to 0.5Mpa.
Disconnect the charge set, and tighten the 2-
way and 3-way valve's stem nuts.
Use a torque wrench to tighten the 3-way
valves service port cap to a torque of 18N.m.
Be sure to check for gas leakage.
2. Air purging with vacuum pump
1) Completely tighten the flare nuts of the
indoor and outdoor units, confirm that
both the 2-way and 3-way valves are set
to the closed position.
2) Connect the charge hose with the push
pin of handle lo to the 3-way valves gas
service port.
3) Connect the charge hose of handle hi
connection to the vacuum pump.
4) Fully open the handle Lo of the manifold
valve.
5) Operate the vacuum pump to evacuate.
6) Make evacuation for 30 minutes and
check whether the compound meter
indicates -0.1Mpa. If the meter does not
indicate -0.1Mpa after pumping 30
minutes, it should be pumped 20 minutes
more. If the pressure can't achieve -
0.1Mpa after pumping 50 minutes,
please check if there are some leakage
points.
Fully close the handle Lo valve of the
manifold valve and stop the operation of the
vacuum pump. Confirm that the gauge
needle does not move (approximately 5
minutes after turning off the vacuum pump).
7) Turn the flare nut of the 3-way valves
about 45° counterclockwise for 6 or
7seconds after the gas
coming out, then tighten the flare nut again.
Make sure the pressure display in the
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