Hey, I just signed up and saw your post.
I had the same problem with my new house, it had a cheap A/C system to begin with, but I added more fans in the attic.
I added one electric and that actually cost me some loot each month, I removed the electric fan and installed 3 solar powered attic fans. I have Ridge vents that the house was build with along with the soffets.
I am not sure how hot your attic is, mine was crazy! I also laid down 3 inches of the 'blow in' type of insulation, this made a world of difference even with my crappy A/C unit.
You may need a bigger A/C unit or maybe even a dual zone system, but honestly, I would make sure that your attic is WELL vented. I live up in Delaware and my 2 story house has an attic size of about 900sqft. The tallest point in the A style roof is about 8 to 10 feet.
I also went and installed a solar powered attic fan above the garage in that attic and that also made a difference.
Right now, I have a gable end fan at each end, and one in the center through the roof.
Florida is crazy hot, so I am not even sure what you will need.
BTW: The Solar fans run in the winter too, as the electric will only kick on with heat or humidity. This way it will bring the warmer air in during the winter months for those of you who do not live in florida.
I calcualted about a 40 dollar savings each month and noticed a difference in a matter of hours as to the temp upstairs.
Last edited by silentdub; 06-29-2010 at 09:35 AM.