A/C Guys...fan on question...

If you put it in fan mode, the inside fan will always be on. The compressor outside will still turn on and off based on your thermostat setting.

With the "fan on" as opposed to "auto" the fan will run indefinitely regardless of the compressor. The compressor still cycles based on your thermostat setting. The point of this setting is to keep the air circulating in your house to help prevent it from getting "stuffy" feeling inside.

Similar to those old attic fans that were ceiling mounted except that those were there specifically to ventilate air though the house from windows and screen doors and out into the attic to create a wind tunnel effect. The "always on" setting for your blower fan on your central air unit is there to circulate air within the house. Not as effective really and burns electricity. Also wears out blower fan bearings faster and clogs your filter faster.

quote:

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Does the compressor outside still cycle on and off when you switch to fan?

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yes, the fan on/auto button just controls the inside fan

as long as the other button is set to "cool" then it turns the outside unit on or off as needed to maintain temperature that it is set to.

one thing to keep in mind is when the outside unit is off and you have the fan in the "on" position, it picks up "some" warming from the air circulating through the ducts in the attic.

you only really want to do this if its freezing up, but your trying to stay cool by letting it melt the ice between cooling cycles so it stays able to cool the house until the guy can get there to add freon or clean your indoor coils to fix the problem