What temperature will a two and a half ton AC unit be able to keep a 1200 sq ft house when the outside temp is over 103 degrees?

Answer 1

Very Difficult question to answer. When an air conditioning system is properly designed, it is done with what is called a Manual J. Here is where the location of the structure, the types of building materials that have been used, the direction of exposure of the building and your outside maximum design temperature. Some people use a rule of thumb and say install 1 ton of A/C for every 400 to 600 sq ft. Some get lucky with this, some don't. If your system is of a normal design, it is sized to maintain a 25 degree difference from the out side temperature. Some contractors use 20 degrees. If your average high is 95 outside, you may be closer to the 20 degree which would maintain 75 degrees inside with everything working properly. If 103 is not "average" for your area, then your unit will not keep you lower than 80 degrees during this Peak period.