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Installation
Air Purging
Air purging
The 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 refrigeration system.
Therefore, after evacuating the system, take a leak test for the piping and tubing between the
indoor and outdoor unit.
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.
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.
1. 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.
2. 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.
22 Room Air Conditioner
Indoor unit
Outdoor unit
Manifold valve
Pressure
Lo
Hi
gauge
Charge hose
Nitrogen gas
cylinder(in vertical
standing position)
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