Carrier 19XL - Manual (Page 168)

adding the condenser charge to the cooler charge listed in Table 9 .
Always operate the condenser and chilled water pumps during charging operations to
prevent freeze-ups. Use the Control Test Terminate Lockout to monitor conditions and start the
pumps.
If the machine has been shipped with a holding charge, the refrigerant will be added through
the refrigerant charging valve ( Figure 27 and Figure 28 , valve 7) or to the pumpout charging
connection. First evacuate the nitrogen holding charge from the vessels. Charge the refrigerant
as a gas until the system pressure exceeds 68 psig (469 kPa) for HCFC-22; 35 psig (141 kPa)
for HFC-134a. After the machine is beyond this pressure the refrigerant should be charged as a
liquid until all of the recommended refrigerant charge has been added.