Thermostatic Expansion Valve (TXV)

 
This twisty part which is found in an A/C unit regulates the refrigerant flow for the indoor coil.  It is called a thermostatic expansion valve, or TXV, for short.  The TXV makes sure the A/C unit maintains maximum efficiency by allowing only a certain amount of refrigerant to flow into the evaporator. This control over the flow of refrigerant is necessary to make the evaporator as efficient as possible. It also prevents refrigerant from flowing back into the compressor. There's a pretty good video on YouTube that shows you how it works. 

What the Thermostatic Expansion Valve Doesn't Control

Controlling the flow of refrigerant is the function of the TXV. It doesn't control any of the following:

1. Air Temperature

2. Head Pressure Capacity

3. Suction Pressure

4. Humidity

What Makes the TXV Fail

This part usually holds up pretty well. When it does fail, it's usually in the middle of summer, when the extremely high outdoor temperatures just cause everything to malfunction and break down.  There are a few ways to keep the TXV running for as long as possible. However, there are a few things that will make the thermostatic expansion valve fail:
1. Under sized return duct work,

2. Improper refrigerant charge

3. Improper factory installation

It is very important to have the air conditioner installer inspect the TXV carefully to make sure the duct work is the proper size and that the refrigerant charge is accurate according to the manufacture’s specifications.

The TXV is one of the more pricey parts to replace on your air conditioner, so you'll want to make sure the above items are taken care of as necessary.  Clark Heating & Cooling will gladly check these for you!  Call us today!