undersized a/c unit
I bought a foreclosure last year 3800 sq feet. (Charlotte NC) a/c unit is 3.5 tons.(only one unit). Have a dual zone system (two thermostats one upstairs one downstairs). The system heats fine but cooling during 90+ days is not adequate. Will cool entire home by about 10 degrees on hot days so we only use one zone when it is hot out. It will cool one zone down about 20+ degrees making the other zone basically uninhabitable. My furnace is a Bryant 310aav048090 (the system is still under warranty). The hvac company that installed the system states that the 3.5 ton a/c system is the right size for my home but i am nearly positive that this is not so. Based on what i read it should be around a 5-6 ton system. What are my options? Would the HVAC company be responsible in anyway for such a undersized system?