What is TXV?
Plain-English explanation from a licensed Utah HVAC, plumbing, and electrical contractor.
A TXV is the metering device that controls refrigerant flow into your AC's indoor evaporator coil — it adjusts continuously based on cooling load, making the system more efficient than older fixed-orifice systems.
Full Definition
A Thermostatic Expansion Valve (TXV, or TEV) is a refrigerant flow control device mounted at the inlet of the evaporator coil. A bulb senses the temperature of refrigerant leaving the coil and signals a diaphragm to open or close the valve seat, maintaining a constant superheat across varying loads. TXVs replaced fixed orifice (piston) metering devices in residential systems around 2006 as efficiency standards rose.
TXV failures cause cooling capacity loss and high energy bills — symptoms include long run times, warm air from registers, frosting at the indoor coil, or a stuck-closed valve causing no cooling at all. Replacement runs $589–$889 and requires recovering and recharging the refrigerant. A failed TXV is sometimes confused with low refrigerant.
Common Questions
How do I know if my TXV is bad?
Symptoms include very low suction pressure, abnormal superheat readings, frosting at the indoor coil while outdoor temps are mild, or a sudden drop in cooling capacity. A tech with proper gauges and a digital thermometer can confirm in 15 minutes.
Can a TXV be repaired or just replaced?
TXVs are sealed assemblies — they're replaced, not rebuilt. The good news is the rest of your AC's lineset, coil, and refrigerant charge usually transfer over fine after the TXV swap.
Related Terms
Refrigerant
Refrigerant is the working fluid inside an AC or heat pump — it absorbs heat indoors and releases it outdoors as it cycles between liquid and gas states.
AC Compressor
The compressor is the heart of your air conditioner or heat pump — it's the pump that circulates refrigerant through the system, and replacement is by far the most expensive HVAC repair.
Recent HVAC work in Utah
A few installs and service calls from the AYSP crew.
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