When I have the a/c on we get a lot of flies in are down stairs kitchen sometimes they are on the inside window other times there in between the screen and glass part of the window.
Now when we turn of the A/C the flies go away.Do you have any idea of how the flies are getting in the house with the doors and windows locked.Could you please Help.

Flies come from maggots and flies will lay eggs on just about anything that is rotting (garbage, etc.) We have a lot of flies in our garage because that's where our garbage is and therefore maggots, in the hot weather. Think about it and check around.

And flies pass the winter as adult flies sleeping in crevices. They could have climbed into your AC unit and are being blown out when it's turned on. Probably they like the kitchen because it's a little warmer than other rooms or they're attracted to food odors. They also like the color yellow. Yellow wallpaper? Yellow curtains?