NATE Air Distribution Practice Test

Reducing the cooling blower speed impacts the airflow across the evaporator coil, which in turn influences the temperature difference between the refrigerant and the air passing over the coil. When the blower speed is decreased, the air movement slows down. This can lead to a greater time for the air to absorb heat from the evaporator coil, allowing the refrigerant to cool the air more effectively over that extended time.

As a result, the temperature drop across the evaporator coil can increase because the cooling effect from the evaporator is more pronounced with slower airflow. Slower air movement allows for more thorough cooling as the air has increased contact time with the coil, rather than quickly passing over it and not absorbing as much heat.

Therefore, when blower speed is reduced, the overall temperature drop across the evaporator coil will likely increase, making this the correct interpretation of the effect that changing blower speed has on cooling efficiency.