Where is the thermal expansion valve on a residential AC system?

Answer 1

Hi: thermal expansion valve (TEV) valve, are not always used on residential Air Conditioning Units. If you do happen to have one it will most likely be close to your evaporator coils and housed with them ( cooling coils) and a dead give away is a tiny copper looking line with a sensor clamped and insulated to the big cold refrigeration valve just beyond the coil on its was back to the compressor. Capillorary tube systems have been used for the big majority of domestic home installations of last couple few decades. Unlike the T.E.V. valve , they just have a fixed orifice that never changes and of course are a good way to cut cost. They are not bad but not great either. T.A.V. valves are much like their cousins T.E.V. valves but do not sense down stream evaporator temperature but pressure to make their variable adjustments to load demands. Very usefull and very effective yet not quite up to par with the T.E.V. valves in the all around performance and efficiency catagory. Heat Pumps can use the T.E.V. valves as well as none heat pumps in case you wonder. So you may see them located outside on those units as well. Superheat is of great importance in setting these devices and selecting their placements. Be sure they are strapped well to the copper suction line and have good insulation. Also make sure the tiny capillary refrigerant lines to them have not mean crimped or worn through by vibration or cut in some manner as this will render the automation of this device useless and it will then be fixed orifice device and not variable which means loosing its most qualific edge. Do Not Attempt to Recharge or adjust these T.E.V. valves: Their Bulb charges may not be at all the same as that of the system and ususally are not. Replace only, with same kind and in same order as original. Hope this helps: Jimiwane