It’s a common misconception that the cooling blower speed on a residential air conditioning system should always be set to “high.” In many cases high speed for cooling will not give you the best possible performance and customer comfort.
If the blower speed is set too high for the application, the evaporator coil will not be able to do an adequate job of dehumidification, and may result in a customer complaint. If the blower speed is set too low, you risk “freezing” the evaporator coil, which could lead to compressor failure due to liquid refrigerant floodback. Therefore, it is imperative that the proper blower speed for air conditioning is used.