July Tech Challenge — Answer
A commercial rooftop utilizing R-410A with a TXV feed device (and receiver) has a customer complaint of “insufficient cooling.” The symptoms confirm inadequate cooling and the compressor appears to be running all of the time and the thermostat is not satisfied. What are the “possible causes” (Note: There is only one problem intended) with the following measured conditions on this field service check sheet?
It appears to be a restricted air flow over the condenser caused from a dirty condenser, diverted air flow, or condenser fan issue. The condensing pressure/temperature, and condenser split are high to expel the heat gained in the evaporator, superheat and compressor. The high compression ratio is causing recompression, high discharge temperatures, and high amperage. The subcooling and superheat are high to normal because the TXV is attempting to maintain a constant S.H. with a lower refrigerant flow caused by the higher compression ratio.
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