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• Read all notes and warnings for the Cooling-mode charging charts prior to using these Heating-mode
charge verification charts. Always use safe and environmentally sound methods when handling refrigerant
handling or servicing the unit. Review the factory literature and safety warnings prior to servicing.
• When repairing system leaks, always use a nitrogen (inert) gas to protect the refrigerant system and pressure
check the repair before re-charging. Always replace the filter-dryers when performing any repair to the refrigeration
system with one capable of acid removal. After completing the repairs, evacuate the system to 350 - 500 microns
and weigh in the refrigerant to the amount specified on the unit rating label.
• Before using the heat mode verification tables (Tables 3 - 9, pages 15 - 17), determine the outdoor ambient
temperature and the return air temperature to the unit. Locate the appropriate location on the units verification
chart based on those measurements to determine the ideal liquid line pressure and temperature. Verify the outdoor
fan and compressor are running and the outdoor coil is free from frost accumulation. Also verify the system is not
operating in defrost mode before inspecting the system.
• Always use quality instruments that are in good working order to measure the actual operating point of the
refrigeration system. The liquid line temperature should be within 2 degrees of the ideal value and the pressure
should be within 2%.
• The most reliable way of verifying the system is at the correct charge is to evacuate the system and weigh in the
charge to the amount shown on the rating label. However, if an inspection with these verification charts does not
line up with the values shown and the ambient temperature is above 50˚ F, then a more accurate way to inspect
the system for proper charge is with the cooling mode charging charts. Switch the unit into cooling mode and
allowittooperateandstabilizeforafewminutestheninspecttheunitoperationwiththecoolingmodechartsand
procedures.
Before changing the unit charge, always inspect the following items first:
1. Inspect the liquid line temperature on the inlet and outlet of the filter dryers. If it is the factory dryer and in good
condition there should be no temperature difference. If the temperature difference is larger than 5˚, replace the filter
dryer with one that is bi-directional and has acid removal capability. Refer to the unit RPL for the recommended
partnumberandsize.
2. Inspect the units input voltage. Units operating at less than 95% of the nominal voltage may deviate more from the
chart then previously stated.
3. Inspect the input voltage for a phase imbalance. Units with greater then a 2% disparity will not operate at the rated
performance.
4. Verify that the unit filters are installed and are clean. The pressure drop across the filters should not exceed 0.08
in-W.C.
5. Inspect the indoor coil, indoor blower and blower motor for cleanliness, clogging, and proper operation.
6. Inspect the system for leaks. If any leaks are detected, repair them immediately. Re-inspect the return air and
ambient temperatures and verify that the correct system point on the verification chart was selected.
DO NOT use the charts in systems that have the fan cycling under a low-ambient control. Low-ambient controls are
for cooling operation. In heating mode, the low ambient control should be disabled. Unless the unit is in defrost mode,
the outdoor fan should always operate in conjunction with the compressor.
Application Notes on the use of Heating-mode charge verification charts:
NOTES:
1. All pressures are listed psig and all temperatures in °F
2.
Discharge temperatures greater than charted values
indicate an undercharged system
.
LEGEND
Shaded boxes indicate flooded conditions.
Rated design values. Suction pressure will
vary from design value if outdoor air flow,
entering dry bulb, or entering wet bulb
temperatures vary
.
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