Air Purging - LG MFL39817303 Installation Manual

Air Purging

Air purging
The 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, after evacuating the system, take a leak test for the piping and tubing between the
indoor and outdoor unit.
Air purging with vacuum pump
1. 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. Note that both the liquid and the gas side
service valves on the outdoor unit are kept closed at this stage.
2. Leak test
• Connect the manifold valve(with pressure gauges) and dry nitrogen gas cylinder to this service port with
charge hoses.
Be sure to use a manifold valve for air purging. 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.
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 leak 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.
Indoor unit
Outdoor unit
Nitrogen gas
cylinder(in vertical
standing position)
Installation
Manifold valve
Lo Hi
Charge hose
Installation Manual 25