Midea MTA-76C(H)RN1 Technical Manual page 84

Midea R410A T3 Top-discharge Split Type Series 50Hz

Use a vacuum pump

Loosen and remove the maintenance orifice nut of valve A, and connect the filler hose
of the manifold valve to the maintenance orifice of valve A (Tighten both valve A and
valve B).

Connect the filler hose adapter to the vacuum pump.

Open the low (Lo) pressure handle of the manifold valve completely.

Start the vacuum pump to extract air. At the beginning of extracting air, slightly loosen
the maintenance orifice nut of valve B, check whether any air enters it (The vacuum
pump noise changes, and the multi-meter indicates from negative to 0.). Then tighten
this maintenance orifice nut.

Upon completion of vacuuming, tighten the low pressure handle of the manifold valve
completely and stop the vacuum pump. Keep extracting air for over 15 minutes. Check
whether the multi-meter points at -1.0×10Pa (-76cmHg).

Loosen the remove the square-head cover of valves A and B. After opening valves A
and B completely, tighten the square-head cover of valves A and B.

Remove the filler hose of the maintenance orifice of valve A, and then tighten the nut.

Procedure of using stop valve

Open the spool until it touches the stop block. Do not attempt to open further.

Use a spanner or a similar tool to tighten the bonnet.

Upon completion of installation, open all valves before trial run. Each unit has two valves of
different sizes located at the outdoor unit side. Of the two valves, one is gas valve and the
other is liquid valve. The procedure of opening / closing the valve is shown in following
83
MCAC-UTSM-201501