Why must you avoid running a refrigeration system below 14 KPa when pumping down?

Running a refrigeration system below 14 KPa during a pump-down can lead to air infiltration, which can severely compromise the system's efficiency and performance. A positive system pressure is essential because it helps maintain a barrier that prevents the entry of moisture and air into the refrigerant lines. Air infiltration can cause a variety of problems, including decreased system efficiency, potential corrosion of components, and refrigeration cycle inefficiencies. By keeping the system pressure above this threshold, you help to ensure that the refrigerant remains contained and that the system operates within safe parameters, ultimately protecting its functionality and longevity.