What Are Some Signs That Your Air Conditioner's Thermostatic Expansion Valve Is Clogged?

Posted on: 11 October 2022

The thermostatic expansion valve inside your home's air conditioning system is what transforms refrigerant from liquid to gas. As the refrigerant passes through the valve, it decreases in pressure and expands in volume. The refrigerant becomes much colder as it turns into a gas, allowing it to absorb heat from the air inside your home. After absorbing heat from the inside air, the gaseous refrigerant is sent to a compressor that turns it into a liquid again.

When a thermostatic expansion valve is functioning normally, your air conditioner will be able to keep the air in your home cool and comfortable. However, they can become clogged by oil from a leaking compressor or debris that enters the system. When this happens, you'll need to have the thermostatic expansion valve cleaned or replaced by an HVAC repair service. If your home's air conditioner isn't working correctly, read on to learn more about the problems that can be caused by a clogged thermostatic expansion valve.

Ice-Cold Air and an Overheating Compressor

When a thermostatic expansion valve is clogged, less refrigerant will flow through it. A lower volume of refrigerant flowing through the valve will result in it expanding and cooling down too much when it's depressurized. The temperature of the evaporator coils the gaseous refrigerant flows through will become very low as a result, allowing the refrigerant to absorb more heat from the air inside your home.

Your air conditioner will be able to cool your home very quickly since it's absorbing more heat from the air. The extra-cold refrigerant will also cause the evaporator coils to pull more moisture from the air, dehumidifying your home. While this may sound like a benefit, it can cause damage to your air conditioning system.

The extra heat absorbed by the refrigerant will travel to the compressor, which already produces a substantial amount of heat on its own as it turns the refrigerant back into a liquid. This can result in your compressor overheating, which will shorten its lifespan.

Warm Air From Your Air Conditioner and Frost-Covered Evaporator Coils

If the clog in the thermostatic expansion valve worsens, only a trickle of refrigerant will enter the evaporator coils. This causes the refrigerant to become extremely cold, and it will eventually lower the temperature of the evaporator coils below the freezing point. Frost will begin to collect on the coils, and they may eventually turn into a solid block of ice.

The ice on the coils will insulate them and block airflow, so the refrigerant won't be able to absorb any heat from the air. As a result, you'll feel warm air blowing from your home's air conditioner.

If you think that your home's air conditioner has a problem with its thermostatic expansion valve, have it inspected by an HVAC repair technician. Only a licensed HVAC technician is allowed to repair or replace a thermostatic expansion valve since it has refrigerant flowing through it. All of the refrigerant needs to be drained from your home's air conditioner before any repairs can be made, and only an HVAC repair service can legally work with refrigerant. Once you have your thermostatic expansion valve repaired or replaced to unclog it, you'll be able to use your air conditioner again without worrying about damaging your system or your evaporator coils freezing


Summer is Upon Us – Is Your AC Working?

Hi. My name is Laurie Waters. The HVAC contractor was just out at our house last week and did I ever get a lesson from him. You see, we had a warm spell hit and I went to turn our air conditioning on for the first time since last summer. Much to my dismay, it wasn’t working. All I got was a blast of warm air. The fan was bringing the outdoor heat inside. Thank goodness it wasn’t anything major. My unit needed Freon. While he was here, the contractor taught me how to do some routine maintenance around my unit, vents, and filters. I’m going to share this information with you. I hope you find it to be useful.

Latest Posts