Help

I have two ceiling fans on the back porch that work perfectly fine when they are on alone. I also have a flood light back there. When the switch to the flood light is on, the fans stop working. Any ideas?

So many possibilities, it is hard to describe them. Obviously, something is wired wrong, but where, and what, without some testing, it is really impossible to tell.

Are any of the things on 3-way switches? Are the fans switched individually, or in tandem? Sorry, without some more info, everything would be a wild guess.

The fans could be wired through the light bulb so that it is the neutral when its switch is off, but there would be no neutral when the light is turned on.(Such as by connecting the fan's white neutral to the "white" switched leg from the toggle switch.) Normally, if that were done, the bulb should "glow" when the fan is turned on, and the fan would run slower, but the current flow could be so low that you would not notice it.