LG MU3M21.UE0R0 User Manual download pdf (Page 28)

28 Multi Air Conditioner

Air Purging and Evacuation

Air and moisture remaining in the refrigerant system have undesirable effects as indicated below.

1. Pressure in the system rises.

2. Operating current rises.

3. Cooling(or heating) efficiency drops.

4. Moisture in the refrigerant circuit may freeze and block capillary tubing.

5. Water may lead to corrosion of parts in the refrigeration system.

Therefore, the indoor/outdoor unit and connecting tube must be checked for leak tight, and

vacuumed to remove incondensible gas and moisture in the system.

Preparation

• Check that each tube(both liquid and gas side

tubes) between the indoor and outdoor units have

been properly connected and all wiring for the test

run has been completed. Remove the service

valve caps from both the gas and the liquid side

on the outdoor unit. Check that both the liquid and

the gas side service valves on the outdoor unit

are kept closed at this stage.

Leakage test

• Connect the manifold valve(with pressure gauges)

and dry nitrogen gas cylinder to this service port

with charge hoses.

CAUTION:

Be sure to use a

manifold valve for leakage test.

If it is not available, use a stop valve for

this purpose. The "Hi" knob of the

manifold valve must always be kept

close.

• Pressurize the system to no more than 150

P.S.I.G. with dry nitrogen gas and close the

cylinder valve when the gauge reading

reached 150 P.S.I.G. Next, test for leaks with

liquid soap.

CAUTION:

To avoid nitrogen

entering the refrigerant system in a

liquid state, the top of the cylinder must be

higher than its bottom when you

pressurize the system. Usually, the cylinder

is used in a vertical standing position.

1. Do a leakage test of all joints of the

tubing(both indoor and outdoor) and both gas

and liquid side service valves.

Bubbles indicate a leak. Be sure to wipe off

the soap with a clean cloth.

2. After the system is found to be free of leaks,

relieve the nitrogen pressure by loosening

the charge hose connector at the nitrogen

cylinder. When the system pressure is

reduced to normal, disconnect the hose from

the cylinder.

Checking method

Charge hose

Nitrogen gas

cylinder(in vertical

standing position)

Indoor unit

Outdoor unit

Lo Hi

Manifold valve

Pressure

gauge

1 2 ... 23 24 25 26 27 28 29 30 31 32 33 ... 36 37

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LG MU3M21.UE0R0 User Manual Page 28

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