ICP HMC009KD, Service Manual

Page: 38 / 83

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(6) 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 corrossion 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.
1)Air Purging with a Vacuum Pump
§
Preparation
Check that each tube(both liquid and gas side tubes)
between the indoor and outdoor units has been properly
connected and all wiring for the test run has been
completed. Remove the valve caps from both the gas
and the liquid side service valves on the outdoor unit.
Note that both liquid and gas side service valves on the
outdoor unit are kept closed at this stage.
§
Leak test
1. 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.
2. 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.
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 vertial standing position.
3. 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.
4. After the system is found to be free of leaks, relieve the
nitrogen pressure by loosening the charge hose
connnector at the nitrogen cylinder. When the system
pressure is reduced to normal, disconnect the hose from
the cylinder.
Lo Hi
Indoor unit
Outdoor unit
Manifold valve
Charge hose
Nitrogen gas
cylinder
(in vertical
standing position)
Pressure
gauge