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64
vacuum pump. Confirm that the gauge
needle does not move (approximately 5
minutes after turning off the vacuum pump).
7) 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.
8) Fully open the 2 way valve and 3 way
valve and securely tighten the cap of the 3
way valve.
2. Air purging by refrigerant
Procedure:
1). Confirm that both the 2-way and 3-way
valves are set to the closed position.
2). Connect the charge set and a charging
cylinder to the service port of the 3-way valve.
3). Air purging.
Open the valves on the charging cylinder and
the charge set. Purge the air by loosening the
flare nut on the 2-way valve approximately 45’
for 3 seconds then closing it for 1 minute; repeat
3 times.
After purging the air, use a torque wrench to
tighten the flare nut on the 2-way valve.
4). Check the gas leakage.
Check the flare connections for gas leakage.
5). Discharge the refrigerant.
Close the valve on the charging cylinder and
discharge the refrigerant by loosening the flare
nut on the 2-way valve approximately 45’ until
the gauge indicates 0.3Mpa (43.5Psi) to 0.5
Mpa (72.5Psi).
6). Disconnect the charge set and the charging
cylinder, and set the 2-way and 3-way valves to
the open position.
Be sure to use a hexagonal wrench to operate
the valve stems.
7). Mount the valve stems nuts and the service
port cap.
Be sure to use a torque wrench to tighten the
service port cap to a torque 18N·m.
Be sure to check the gas leakage.
12.4.4 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. If the refrigerant is
R410A, make 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).
3) Put the charging cylinder onto the electronic
scale and record the weight.
4) Operate the air conditioner at the cooling
mode.
5) Open the valves (Low side) on the charge set
and charge the system with liquid refrigerant.
6).When the electronic scale displays the
proper weight (refer to the gauge and the
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