Is it more energy-efficient to set the central A/C fan to "auto" or "on"? What are the pro's and con's of either setting?:confused:

Auto is best unless you have a special variable speed device that takes the motor down to 300 to 500 rpm when not heating or cooling.
Many reasons but in ac mode the high speed movement of air when the outside unit is off just tosses the humidity back into the air that you just paid to remove.

If you leave the blower at on it will just move the air all the time. That could promote better air circulation but at a very high cost.
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