I live in SOuth FLorida and it has been very hot. I dread the summer because my AC does not seem to cool properly. The unit is about 5 years old and is functioning fine. I was told that I may not be pushing enough air. My T stat is at one end of the house and the return is at the other. The return is 18x29 and I am cooling, or trying to cool 2,000 sqft. I have a 4 ton unit. It was suggested that install an additional return a little closer to the t-stat. Not as big as the main return and no larger than 10x10. I can do this with out a problem, but I do not want to go cutting holes in the ceiling if this is a fix. Any siggestions?

Right now you are border line at 500 sq ft per ton of cooiling for your area. Before you spend any more time or money on this problem you need to have a professional do a manual J to figure out the exact amount of cooling you need. Doing anything else right now would be a waste of time and money.

A manual J takes all of the house items sq ft, window sizes and types,insulation factors etc into account so you will have a REAL size number to work with.

Once you get the correct amount of BTU's needed for your house then you can take corrective action based on the facts.

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Total static pressure before the coil and after the filter should not exceed .5" of water colum an expert using pressures across the equipment sould be able to tell if the problem is a return, supply, dirty coil or a to restrictive air filter problem.

If this equipment uses an ECM motor the static pressure across the blower can go up to .8" W.C.

Putting in an ECM motor can help this problem and increas the efficiency by more than 1 SEER rating.