Air Purging; Air Purging With Vacuum Pump - LG AS-H0764DM0 Service Manual

Air purgingd

AIR PURGING

Air purging
Air and moisture remaining in the refrigerant system have
undesirable effects as indicated below.
• Pressure in the system rises.
• Operating current rises.
• Cooling(or heating) efficiency drops.
• Moisture in the refrigerant circuit may freeze and block cap-
illary tubing.
• Water may lead to corrosion of parts in the refrigeration
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.

Air purging with vacuum pump

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 complet-
ed. 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.
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.
30 Room Air Conditioner
• Do a leak test of all joints of the tubing(both indoor and out-
door) and both gas and liquid side service valves.
Bubbles indicate a leak. 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.
Manifold valve
Pressure
Lo
gauge
Indoor unit
Outdoor unit
Hi
Charge hose
Nitrogen gas
cylinder(in vertical
standing position)