100
AGZ 026B through 130B
IOMM AGZ-5
Procedure to charge a moderately undercharged AGZ unit:
1. If a unit is low on refrigerant, you must first determine the cause before attempting
to recharge the unit. Locate and repair any refrigerant leak. Evidence of oil is a
good indicator of leakage, however, oil may not be visible at all leaks. Liquid leak
detector fluids work well to show bubbles at medium size leaks but electronic leak
detectors can be needed to locate small leaks.
2. Add the charge to the system through the suction shutoff valve or through the
Schrader fitting on the tube entering the evaporator between the compressor and
the evaporator head.
3. The charge can be added at any load condition between 25-100% load per circuit
but at least two fans should be operating per refrigerant circuit, if possible. The
suction superheat should be in the 8 to 12 degree F (4.4
°
C-6.6
°
C) range.
4. Add sufficient charge to clear the liquid line sight glass and until all flashing stops
in the sight glass.
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 15 and 20 degrees F (8.3 and 11.1 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 to 10
°
F (2.8
°
C to
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.
Warranty Statement
Limited Warranty
Consult your local McQuay Representative for warranty details. Refer to Form 933-
43285Y. To find your local McQuay Representative, go to www.mcquay.com.
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