69
Fig. 7-5
Fig. 7-6
The required time in the above table is calculated based on the
assumption that the ideal (or target) vacuum condition is less
than –14.7 psig (–755 mmHg, 5 Torr).
(2) When the desired vacuum is reached, close the “Lo” knob of
the manifold valve and turn off the vacuum pump. Please
confirm that the gauge pressure is under –14.7 psig
(–755 mmHg, 5 Torr) after 4 to 5 minutes of vacuum pump
operation.
Charging additional refrigerant
● Charging additional refrigerant (calculated from the liquid
tube length as shown in Section “1-8. Additional Refrigerant
Charge”) using the liquid tube service valve. (Fig. 7-5)
● Use a balance to measure the refrigerant accurately.
● If the additional refrigerant charge amount cannot be charged
at once, charge the remaining refrigerant in liquid form by
using the gas tube service valve with the system in cooling
operation mode at the time of test run. (Fig. 7-6)
Finishing the job
(1) With a hex wrench, turn the liquid tube service valve stem
counter-clockwise to fully open the valve.
(2) Turn the gas tube service valve stem counter-clockwise to
fully open the valve.
(3) Loosen the charge hose connected to the gas tube service
port (5/16") slightly to release the pressure, then remove the
hose.
(4) Replace the 1/4 in. flare nut and its bonnet on the gas tube
service port and fasten the flare nut securely with an
adjustable wrench or box wrench. This process is very
important to prevent gas from leaking from the system.
(5) Replace the valve caps at both gas and liquid service valves
and fasten them securely.
This completes air purging with a vacuum pump. The air condi-
tioner is now ready for a test run.
