Relevant question:

How air may be removed from the system.

1)Air will finally be accumulated in the condenser.

2)Shut the condenser refrigerant outlet valve if the liquid level is very low.

3)Connect a refrigerant recovery bottle to the purging cock (of the condenser) via a flexible hose.

4)Remove the air until the flexible hose is cold or/and the cooling water difference temperature of about  8-10 degree Celsius is achieved.