My house has 1950 square feet and is a single story. The house is a Fox & Jacobs house built in the early '70s. The current A/C unit is a 3 ton and I believe it is the original unit. I live in the Dallas, TX area (Very hot in the summer). It is time to get a new unit. Should I get a 3.5 ton or a 4 ton?

My house has 1950 square feet and is a single story. The house is a Fox & Jacobs house built in the early '70s. The current A/C unit is a 3 ton and I believe it is the original unit. I live in the Dallas, TX area (Very hot in the summer). It is time to get a new unit. Should I get a 3.5 ton or a 4 ton?
Recommended size for your sq ft would be a 4-5 ton unit

CandyKitten's answer seems about right, I am not a contractor but my HVAC contractor advised me 3 ton for a 1600 sq ft home one story located on the Gulf Coast of AL. When you shop, ask the contractor. He is or should be trained to answer correctly.

How well does the current unit work, or at least when it was newer and in good shape? If it was ever able to do the job, it would be a mistake to replace it with a larger unit. How big of a unit you need depends on some other factors that the size of your house. A tight, well insulated house with plenty of shade may do fine with a unit on the small side.

On the other hand, if the old unit ran and ran, but never cooled the house very well, yes, a bigger unit.