On a humid summer day, what should the temperature drop across the evaporator in a properly running central air conditioning system read?

In a properly running central air conditioning system, the temperature drop across the evaporator typically ranges between 15°F and 25°F when the system is operating under humid conditions. This temperature drop is indicative of the system's efficiency in removing heat and moisture from the indoor air.

The evaporator coil's primary function is to absorb heat from the indoor air, which causes the refrigerant within the coil to evaporate and cool the air passing over it. In humid summer conditions, the air's temperature and humidity levels are higher, making it crucial for the air conditioning system to provide an adequate drop in temperature to ensure comfort.

A temperature drop within the specified range not only indicates that the system is functioning properly but also that it is effectively dehumidifying the indoor air. If the temperature drop were significantly lower than this range, it could suggest that the system is underperforming, while a much higher drop could indicate that it is overworking and potentially leading to issues such as freezing of the evaporator coils.