Carrier 17/19EX - Manual (Page 165)

the refrigerant charging valve, ( Figure 7 and Figure 8 ) 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 35 psig (141 kPa). 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.
Trimming Refrigerant Charge
The 17/19EX is shipped with the correct charge for the design duty of the machine. Trimming
the charge can be best accomplished when design load is available. To trim, check the
temperature difference between leaving chilled water temperature and cooler refrigerant
temperature at full load design conditions. If necessary, add or remove refrigerant to bring the
temperature difference to design conditions or a minimum differential.