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Service Manual -
VMH 9/12/18/24 SU & VMH30/36S D Series
10
12
6.4 I
nitial I
nstallation
Air and moisture in the refrigerant system have
undesirable effects as 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 refrigerant system.
Therefore, the indoor unit and the pipes
between indoor and outdoor units must be
leak tested and evacuated to remove gas and
moisture from the system.
Gas leak check (soap and water method):
Apply soap water or a liquid neutral detergent
on the indoor unit connections or outdoor unit
connections by a soft brush to check for
leakage of the connecting points of the piping.
If bubbles form, the pipes have leakage.
1. Air purging with vacuum pump
1)
Completely tighten the flare nuts of the
indoor and outdoor units, confirm that both
the 2-way and 3-way valves are set to the
closed position.
2)
Connect the
low pressure
charge
hose to
the 3-way
valve
'
s gas service
port.
3)
Connect the
high pressure
hose to the
vacuum pump.
4)
Fully open the
handle of the
low pressure
manifold
valve
.
5)
E
vacuat
e
for 30 minutes and check
that
micron gauge reads <500 microns. If not
, it
should be pumped 20 minutes
more. If the
pressure can’t achieve
<500 microns
after
pumping 50 minutes
,
please
check
for
leakage
points. Fully close the
handle valve
of the
low pressure
manifold
set
and stop the
operation of the
vacuum
pump.
Confirm that
the gauge
needle does
not
move
above 500
microns
(approximately
5
minutes after
turning off the vacuum
pump).
6)
Turn the flare nut of the 3-way valves about
45° counterclockwise for 6 or 7seconds
after
the gas coming out, then tighten the
flare nut
again. Make sure the pressure
display in the
pressure indicator is a little
higher than the
atmosphere pressure. Then
remove the
charge hose from the 3
-
way
valve.
7)
Fully open the 2
-
way valve and 3
-
way valve
and securely tighten the cap of the 3
-
way
valve.
6.5 Adding the refrigerant after running
the system for many years
Procedure
1) Connect the charge hose to the 3-way
service port, open the 2-way valve and the
3-way valve.
Connect the charge hose to
the valve at the
bottom of the cylinder.
Turn
the cylinder
bottom up to ensure
liquid
charge.
2) Purge the air from the charge hose.
Open
the valve at the bottom of the cylinder
and
press the check valve on the charge set to
purge the air (be careful of the liquid
refrigerant).