28 Room Air Conditioner
Evacuation
• Connect the charge hose end described in the preceding
steps to the vacuum pump to evacuate the tubing and
indoor unit.
Confirm the "Lo" knob of the manifold valve is open. Then,
run the vacuum pump.
The operation time for evacuation varies with tubing length
and capacity of the pump. The following table shows the
time required for evacuation.
• When the desired vacuum is reached, close the "Lo" knob
of the manifold valve and stop the vacuum pump.
Finishing the job
• With a service valve wrench, turn the valve stem of liquid
side valve counter-clockwise to fully open the valve.
• Turn the valve stem of gas side valve counter-clockwise to
fully open the valve.
• Loosen the charge hose connected to the gas side service
port slightly to release the pressure, then remove the hose.
• Replace the flare nut and its bonnet on the gas side service
port and fasten the flare nut securely with an adjustable
wrench. This process is very important to prevent leakage
from the system.
• Replace the valve caps at both gas and liquid side service
valves and fasten them tight.
This completes air purging with a vacuum pump.
The air conditioner is now ready to test run.
(1) Remove the caps from the 2-way and 3-way valves.
(2) Remove the service-port cap from the 3-way valve.
(3) To open the 2-way valve turn the valve stem counter-
clockwise approximately 90°, wait for about 2~3 sec, and
close it.
(4) Apply a soap water or a liquid neutral detergent on the
indoor unit connection or outdoor unit connections by a
soft brush to check for leakage of the connecting points
of the piping.
(5) If bubbles come out, the pipes have leakage.
Soap water method
Gas side
Liquid side
Cap
Hexagonal wrench
2-way valve
(Open)
3-way valve
(Close)
Required time for evacuation when 30 gal/h vacuum
pump is used
10 min. or more
15 min. or more
If tubing length is less than 10m (33 ft)
if tubing length is longer than 10m (33 ft)
Indoor unit
Outdoor unit
Lo
Hi
Manifold valve
Vacuum pump
Pressure
gauge
Open
Close
Air purging
