A lot of people suggest putting dual electric fans on a z and not a single. They say a double covers more area. Then I did the math and double 10" fan covers 200 sq. inches(10x20) and a single 15" fan comes to 225. So I figured I would get a two speed fan and wire it so that when the ac is on the low speed would always be on and the high speed would override it when the temp. gets high.Does anybody see any problems with this?