I have a 2 story single family home , total HLA 1400-1700. I’ve lived in the house for almost 3 ½ years. The first floor has high ceilings. During the summer I can never get the temperature indoors below 20, 10, nor 5 degrees lower than the temperature outdoors. My a/c is 13 years old. My home warranty sends a tech, and each time they say it's low on freon. I've been told there are no leaks. There isn't any frost. The outside unit is functioning properly. The filters are new. The tech’s only comment, the unit must be too small. It’s still hot in here! Help! What else can be checked by the tech that might have been missed?