Stuck TXV Valve – What a Restricted Coil Looks Like in Real Time

When customers call us because their AC isn’t cooling, the first thought is usually low refrigerant. But sometimes the problem isn’t a leak—it’s a restriction. One of the most common restrictions is a stuck TXV valve (Thermostatic Expansion Valve), and here’s what it looks like in real life.

During a recent service call, Tech Darin opened up the evaporator coil and found heavy ice buildup caused by a TXV valve that wasn’t allowing refrigerant to flow properly. The photos below show the restriction at the coil, making it crystal clear how this issue stops your system from cooling.

What Is a TXV Valve?

The TXV valve regulates how much refrigerant flows into the evaporator coil. It adjusts the flow depending on how much cooling is needed. Think of it like a throttle for refrigerant—when it’s working right, the coil stays evenly cooled.

But when it sticks or clogs, refrigerant flow is reduced or cut off. The result? Ice forming on the coil instead of heat being absorbed from your home.

Why Do TXV Valves Stick?

• Contaminants in the system. Dirt, moisture, or leftover debris from installation can clog the valve.

• Wear and tear. Over time, moving parts can fail or stick.

• Improper refrigerant charge. Overcharging or using the wrong refrigerant mix can damage the valve.

• Moisture + freezing. Even small amounts of moisture in the line can freeze at the valve and cause blockages.

Symptoms of a Stuck TXV Valve

Homeowners may notice:

• Weak or no cooling despite the system running.

• Ice buildup on the indoor coil or refrigerant lines.

• Warm air blowing from vents.

• Higher-than-normal energy bills.

In the photos above, the ice tells the full story: refrigerant wasn’t moving through the coil the way it should.

Why Restrictions Are a Big Deal

A frozen coil isn’t just a nuisance—it can cause:

• System shutdowns. Ice blocks airflow completely.

• Compressor damage. Liquid refrigerant can back up into the compressor, leading to costly repairs.

• Water leaks. When the ice eventually melts, it can overflow the drain pan and cause water damage.

How We Fix It

When a TXV valve sticks, the best solution is usually replacement. At Cool Air M.D., we:

1. Diagnose the restriction at the coil.

2. Remove and replace the faulty TXV valve.

3. Flush the system and ensure proper refrigerant charge.

4. Verify that refrigerant flow and coil operation return to normal.

Pro Tip from Tech Darin

If you notice your AC isn’t cooling and you see ice on the refrigerant lines, turn the system off immediately and call for service. Letting it run frozen can cause more damage.

Final Thoughts

A stuck TXV valve is a perfect example of how small components can cause big problems. The photos here show just how much damage a restriction can do inside your evaporator coil.

At Cool Air M.D., we’ve seen it all, and we have the know-how to get your system back up and running the right way.

“For more details on preventing costly breakdowns, check out our air conditioner repair services