LG LV-B1860RL Service Manual page 34

6. Air Purging of the Piping and Indoor Unit
1) Air purging
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 refrig-
eration system.
Therefore, the indoor unit and tubing between the
indoor and outdoor unit must be leak tested and
evacuated to remove any noncondensables and
moisture from the system.
2) 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.
CAUTION
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.
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.
• Apply a soap water or a liquid neutral detergent
on the indoor unit connection or outdoor unit con-
nections by a soft brush to check for leakage of
the connecting points of the piping. Do a leak test
of all joints of the tubing(both indoor and outdoor)
and both gas and liquid side service valves.
If bubbles come out, the pipes have leakage. Be
sure to wipe off the soap with a clean cloth.
• 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.
Outdoor unit
Pressure
gauge
–34–
Indoor unit
Manifold valve
Lo Hi
Charge hose
Nitrogen gas
cylinder(in vertical
standing position)