McQuay ACZ 045A, Installation, Operation And Maintenance Manual

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102 IOMM ACZ/AGZ-1
3. The charge can be added at any load condition between 25-100% load per circuit but at least twoF
fans should be operating per refrigerant circuit if possible. The suction superheat should be in the
6
°
F-12
°
F (3.3
°
C-6.6
°
C) range.
4. Add sufficient charge to clear the liquid line sightglass and until all flashing stops in the sightglass.
Add an extra 15-20 lbs. of reserve to fill the subcooler if the compressor is operating at 50-100%
load.
5. Check the unit subcooling value by reading the liquid line pressure and temperature at the liquid
line near the filter-drier. The subcooling values should be between 6 degrees F-20 degrees F (6.6
degrees C-11.1 degrees C). The subcooling values will be highest at 75-100% load, approximately 12
degrees F-20 degrees F (6.6 degrees C-11.1 degrees C) and lowest at 50% load, approximately 6
degrees F-12 degrees F (3.3 degrees C-6.6 degrees C).
6. With outdoor temperatures above 60
°
F (15.6
°
C) all condenser fans should be operating and the
liquid line temperature should be within 5
°
F-10
°
F (2.8
°
C-5.6
°
C) of the outdoor air temperature. At
25-50% load the liquid line temperature should be within 5
°
F (2.8
°
C) of outdoor air temperature with
all fans on. At 75-100% load the liquid line temperature should be within 10
°
F (5.6
°
C) of outdoor air
temperature with all fans on.
7. Overcharging of refrigerant will raise the compressor discharge pressure due to filling of the
condenser tubes with excess refrigerant.