LG AS-C306MSeries, Service Manual

Page: 26 / 75

26 Room Air Conditioner
AIR PURGING
Installation
1) 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 capillary tubing.
■
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.
■
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.
■
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.
■
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.
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.
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.
CAUTION
Lo Hi
Indoor unit Indoor unit
Outdoor unit Outdoor unit
Manifold valve
Charge hose
Nitrogen gas
cylinder(in vertical
standing position)
Pressure
gauge
30k 36k