The TXV Valve is a small interactive valve that is installed “inline” on your HVAC systems tubing. Although this valve installation requirement is being phased out with the new 2010 Energy savings mandates, IF you DO have it already in place, it is important to inspect it, make sure that it IS working, and that it does, in fact, VERIFY that your system is performing at the required levels of efficiency.
It is designed to reveal and regulate the correct flow ( pressure and temperature )  of the refrigerant “Freon” that your equipment is designed to operate under.  These pressures and temperatures are meant to be kept within a certain equipment specific range or unnecessary wear and tear can cause your compressor and evaporative coils to fail prematurely.   It’s another relatively easily verification service that can help assure you of cost effective HVAC operations.