If the 4 ton system never kept up and cooled all these years why the sudden urge to upgrade ?

The difference ebwteen a 4 ton and 5 ton isn't goign to make alot of diference to you if the probelm is in inflitration of that hot Oklahoma temperture...

Invest in some good insulationa nd look into better windows and sealing that house up...

As a contractor I sure wouldn't stick my neck out on a 5 ton if the 4 ton was less than marginal... Yopu've got some other issues goign onthere that need to be corrected first and foremost...

I think the options of a VS air hadnler or FAU is great it will help over come any static pressures issues. But until you have the issues corected, isntallign a 2 speed system such as the Infinity System you'll find your self with some dissatisfaction guaranteed....

Have your house carefully evalulated for it's heat loss and gains, you be glad. Especially if you figure out where all this coolness is going...

[Edited by AllTemp on 03-14-2005 at 02:34 AM]