Midea MTA-76C(H)RN1 Technical Manual page 82

Midea R410A T3 Top-discharge Split Type Series 50Hz

Evacuate the vapor line, evaporator and the liquid line, to 500 microns or less.

Replace cap on service ports. Do not remove the flare caps from the service ports except when
necessary for servicing the system.

Do not connect manifold gauges unless trouble is suspected. Approximately 3/4 ounce of
refrigerant will be lost each time a standard manifold gauge is connected.

Release the refrigerant charge into the system. Open both the liquid and vapor valves by
removing the plunger cap and with a hex wrench back out counter-clockwise until valve stem
just touches the chamfered retaining wall.

Replace plunger cap finger tight, then tighten an additional 1/12 turn (1/ hex flat). Cap must be
replaced to prevent leaks.

Never attempt to repair any brazed connections while the system is under pressure. Personal
injury could result.

After the pipes between the indoor unit and the outdoor unit are connected, replenish
compressed nitrogen to perform airtight test.

The airtight test is performed by using the compressed nitrogen, 2.94MPa (30kg/cm
Leak test with a bubble type leak detector. Do not use the system refrigerant in the outdoor
unit to purge or leak test.

Tighten the spool of the low pressure valve and high pressure valve before compressing the
nitrogen.

Compress the nitrogen at the air vent of the gas valve.

The low pressure valve and high pressure valve are closed in the process of compressing
the nitrogen.

Do not use oxygen, flammable gas or toxic gas in the airtight test.

Vacuum
Length of connective pipe
Note: If the air conditioner is relocated, be sure to use a vacuum pump or refrigerant tank to expel air.
81
(Single pass)
Less than 5m
5~15m
Procedure of expelling air
Use refrigerant in the outdoor unit.
Use vacuum pump or refrigerant tank.
MCAC-UTSM-201501
2
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