Air Purging - LG LS-J0761NL Service Manual

5. Air Purging

1) Air purging
Air and moisture remaining in the refrigerant system
have undesirable effects as indicated below.
I Pressure in the system rises.
I Operating current rises.
I Cooling(or heating) efficiency drops.
I Moisture in the refrigerant circuit may freeze and
block capillary tubing.
I 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
I
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 com-
pleted. 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
I Connect the manifold valve(with pressure
gauges) and dry nitrogen gas cylinder to this ser-
vice 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.
I Pressurize the system to no more than 150
P.S.I.G. with dry nitrogen gas and close the cylin-
der 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.
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Only for training and service purposes
I 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.
I 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
gauge
- 38 -
Indoor unit
Outdoor unit
Lo Hi
Charge hose
Nitrogen gas
cylinder(in vertical
standing position)
LGE Internal Use Only