Hello. Newbie here.
I have a 4500 sq. ft. 2-story house in the DFW area. It is 7.5 years old. I have two AC units outside; one large (1st floor) and the other small (for the 2nd floor). The problem is that on very hot summer days, the smaller unit for the 2nd story never shuts off. I can not even get the upstairs temperature down to 81 degrees when the sun is out. My house has tinted windows, adequate insulation and the best radiant barrier foil in the attic. I'm thinking the system installed in my house is not the right size. It is a Lennox. I was interested in any professional feedback. Thanks.