Midea MCHS-09PSH1, Service Manual

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6.4 Installation for the first time
Air and moisture in the refrigerant system have
undesirable effects as below:
●
Pressure in the system rises.
●
Operating current rises.
●
Cooling or heating efficiency drops.
●
Moisture in the refrigerant circuit may
freeze and block capillary tubing.
●
Water may lead to corrosion of parts in the
refrigerant system.
Therefore, the indoor units and the pipes
between indoor and outdoor units must be leak
tested and evacuated to remove gas and
moisture from the system.
Gas leak check (Soap water method):
Apply soap water or a liquid neutral
detergent on the indoor unit connections or
outdoor unit connections by a soft brush to
check for leakage of the connecting points of
the piping. If bubbles come out, the pipes have
leakage.
1. 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(14.5Psi) . If the meter does not
indicate -0.1Mpa(14.5Psi) after pumping 30
minutes, it should be pumped 20 minutes
more. If the pressure can’t achieve
-0.1Mpa(14.5Psi ) 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 pressure indicator is a little
higher than the atmosphere pressure. Then
remove the charge hose from the 3 way
valve.
8) Fully open the 2 way valve and 3 way valve
and securely tighten the cap of the 3 way
valve.
6.5 Adding the refrigerant after running
the system for many years
Procedure:
1). Connect the charge hose to the 3-way service
port, open the 2-way valve and the 3-way valve.
Connect the charge hose to the valve at the
bottom of the cylinder. If the refrigerant is