5
Test Run and Others
1. Air Purging
Fig. 5-1
Fig. 5-2
Air and moisture in the refrigerant system may have
undesirable effects as indicated below.
G pressure in the system rises
G operating current rises
G cooling (or heating) efficiency drops
G moisture in the refrigerant circuit may freeze and
block capillary tubing
G water may lead to corrosion of parts in the
refrigerant 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.
I Air Purging with a Vacuum Pump (for Test Run)
Preparation
Check that each tube (both liquid and gas 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 tube and liquid tube service valves on the
outdoor unit. Note that both liquid and gas tube
service valves on the outdoor unit are kept closed
at this stage.
Leak test
(1) Attach a manifold valve (with pressure gauges)
and dry nitrogen gas cylinder to this service port
with charge hoses.
(2) Pressurize the system to no more than 36 kgf/cm
2
G
with dry nitrogen gas and close the cylinder valve
when the gauge reading reaches 36 kgf/cm
2
G.
Then, test for leaks with liquid soap.
Fig. 5-3
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 closed.
To avoid nitrogen entering the
refrigerant system in a liquid
state, the top of the cylinder
must be higher than the bottom
when you pressurize the
system. Usually, the cylinder
is used in a vertical standing
position.
(Refer to the previous page.)
5 - 2
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