We have been dealing with cooling issues in our home since moving into the new construction in 2005. Our 1.5 ton ran constantly without successfully keeping the home cool, so we opted to upgrade to 3 ton when the a-coil went out in 2008. Since then we have had the txv valve replaced 4 times and the unit is freezing up again! This is the typical problem that results in a new valve. Last year the service/installation company had a "specialist" from Carrier come run some tests but we have never received the results, though we have asked. Also the owner of the heating and cooling company happens to be part owner in the construction company that built our home so I am afraid we would not be told of any possible problems with the duct work. What could be making all of these valves fail year after year? I find it hard to believe they are faulty at this point. Is there such thing as a master hvac tech that could diagnose and fix our real problem? If so, how do we find one? Any input is greatly appreciated.