(4)Do a leak test of all joints of the tubing (both indoor and outdoor) and both gas and liquid service valves. Bub- bles indicate a leak. Wipe off the soap with a clean cloth after a leak test.
(5)After the system is found to be free of leaks, relieve the nitrogen pressure by loosening the charge hose con- nector at the nitrogen cylinder. When the system pres- sure is reduced to normal, disconnect the hose from the cylinder.
Evacuation
(1)Attach the charge hose end described in the preceding steps to the vacuum pump to evacuate the tubing and indoor unit. Confirm that the “Lo” knob of the manifold valve is open. Then, run the vacuum pump. The opera- tion time for evacuation varies with the tubing length and capacity of the pump. The following table shows the amount of time for evacuation:
Required time for evacuation
when 30 gal/h vacuum pump is used
If tubing length is | If tubing length is |
less than 49 ft. | longer than 49 ft. |
|
|
45 min. or more | 90 min. or more |
|
|
Pressure gauge
Gas tube
Liquid tube
Balance tube
Manifold valve
Lo 
Hi
Vacuum pump
Open
Close
Open
Outdoor unit
Close
Open
Close
Fig.
68
