To Reduce Humidity, Set your HVAC fan on Auto
Given the extremely humid days we’ve had here in NC, I’m sure you can feel that drier air is more comfortable air (and it is healthier for you too!)
In the graph above, the blue line represents the dew point, or humidity, of the air. What happened? The sustained increase in humidity resulted from the fan setting being switched to ‘ON’ instead of ‘AUTO’. While the air conditioning cycle was running, the indoor coil got cold. Water vapor from the air passing over it would condense on the coil. When the compressor turned off, the coil would warm up. The water remaining on the coil normally would just sit there until the next cycle, with some of it evaporating and sitting in the air inside the coil housing. But with the fan running continuously, the air passing over the coil as it warmed up would evaporate that water and put it right back into the building.
High relative humidity is also potentially unhealthy. Mold thrives in humid climates.
For more detail on this subject, check out the source of this article at www.energyvanguard.com