Air conditioners consist of many different parts, including a small device known as an expansion valve. How does an air conditioner expansion valve work? We’re going to explain all about AC expansion valves, including what they are, how they function, and how to diagnose and troubleshoot a faulty expansion valve.  

As an Arizona resident, you are well aware that a working air conditioner is worth its weight in gold. Are you having trouble with your AC? Whether the problem is a broken expansion valve, faulty cord, damaged piping, or something else, your first phone call should be to Felix Appliance Repair. We’re proud to be Maricopa’s heating and air conditioning company and offer professional, fast, and affordable HVAC services, including AC repair.

What is an Air Conditioner Expansion Valve?

Expansion valves are an internal mechanism inside air conditioners that serve many purposes: they control the flow of refrigerant, release pressure, and cool off hot air. The most common types of expansion valves include:

In this post, we’ll explain how a thermal expansion valve works, as it’s the most common type for standard air conditioners.

How Does an AC Expansion Valve Work?

In the simplest possible terms, an air conditioner works by sucking in hot air, cooling it off, and sending it back into your home. When the hot air enters the AC, the refrigerant passes over it and absorbs its heat, lowering the temperature. As the refrigerant heats up, it increases in pressure.

Here’s where the expansion valve comes into play: it releases that hazardous pressure buildup, cooling off the air simultaneously. It does this by regulating the refrigerant flow within the liquid line, preventing it from entering the evaporator coil too quickly. Furthermore, this pressure drop also lowers the refrigerant’s boiling point. When the expansion valve limits the refrigerant’s flow, it can spread throughout the open space inside the coil, dropping the pressure and temperature.

How to Tell if the AC Expansion Valve Isn’t Working

When the expansion valve fails on an air conditioner, it can prevent the entire system from working correctly or blowing cool air. If your AC is malfunctioning, you may be eligible for financial assistance to pay for repairs through Maricopa County’s Home Improvement Program. First, though, how can you tell if your AC expansion valve isn’t working? Watch out for these two common signs:

The AC is Blowing Warm Air

Have you noticed the temperature inside your home steadily rising? If your AC has been blowing warm air, the problem could be a faulty expansion valve. Remember, this valve regulates the flow and pressure of the liquid refrigerant inside the air conditioner. A malfunctioning expansion valve negatively affects how the refrigerant changes from a liquid into a gas. Ultimately, it limits how much heat the AC can remove from the air, which means it sends warmer air back into your home.

The AC is Making a High-Pitched Whistling Noise

A damaged or faulty expansion valve can’t regulate the flow of refrigerant into the evaporator coil correctly. When this happens, it often causes the high-pressure refrigerant to flood into the coil quickly and all at once. The high-pressure liquid creates a high-pitched whistling noise as it streams through the faulty valve into the coil.

Common Problems with AC Expansion Valves

Wear and Tear Increases Refrigerant Flow Speed

Like any other mechanical device, expansion valves can fail. When an AC is running, the valve continually withstands extreme pressure from the side connected to the liquid line. After continued use, the valve can wear down, which means it can’t properly regulate the flow of refrigerant and often causes the signs we just discussed above.

Debris Clogs the Valve and Restricts Refrigerant Flow

Another common problem occurs when the expansion valve becomes full of debris. A clogged valve doesn’t allow high-pressure refrigerant to flow into the evaporator coil and create cold air. Plus, this can lead to problems where the hot air enters the AC and may even result in a compressor failure or burnout.

Keep Your AC Running Smoothly with Felix Appliance Repair

So, how does an air conditioner expansion valve work? Basically, it regulates the flow of liquid refrigerant, causing a drop in both pressure and temperature. The best way to prevent problems with your expansion valve is by scheduling regular AC maintenance from the professionals here at Felix Appliance Repair. Our experts will have your AC working properly and blowing ice-cold air before you know it.  

Call Felix Appliance Repair now at 480-406-7487 to book your appointment with our licensed HVAC technicians. ­­­­­­­

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