This troubleshooting problem involves a 5-ton, R-22 rooftop air conditioning unit, and the customer’s complaint is that on days when the ambient temperature exceeds 90°F, the system doesn’t keep the store, which was recently remodeled, comfortable even though it seems to be running continuously.
When you begin your evaluation of this situation, you determine that the evaporator and condenser coils are clean, the air filters are clean, and that there is water in the condensate pan under the evaporator.
You also determine that the evaporator and condenser fan motor are operating normally, the compressor current draw is normal, and the liquid line sight glass is clear. There is no evidence, even after several hours of operation, that there is any shutdown due to safety controls. When you perform a temperature differential check across the filter drier, you find that there is no temperature drop across it.
Figure One shows additional details regarding the refrigerant pressures and air temperatures you find.
Your troubleshooting question: What have you determined about the air handling system of this unit?
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Publication date: 3/5/2018