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Installation
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.
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 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.
24 Room Air Conditioner
• 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.
Outdoor unit
Manifold valve
Pressure
Lo
gauge
Charge hose
Indoor unit
Hi
Nitrogen gas
cylinder(in vertical
standing position)
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