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Cooling systems rely on a complex set of parts to cool air properly, including the compressor and refrigerant lines. Without each part doing its job, your unit cannot cool air to help you escape the heat and humidity. The expansion valve is a particularly nifty little piece that keeps refrigerant flowing, but how does an air conditioner expansion valve work?
Below, Richmond Hill’s air conditioning replacement and installation team from Georgia Air Cooling & Heating explains the different types of expansion valves and the signs of a failing valve.
What is an Expansion Valve?
Expansion valves are pressure valves that control the flow of refrigerant throughout your cooling unit. More specifically, it removes pressure from the refrigerant, making it easier to control and manage.
How Expansion Valves Work
Every modern air conditioning system relies on a refrigerant to cool air. As hot air enters the unit, the refrigerant absorbs it, causing an increase in pressure. This crucial step makes the air conditioning process possible, but it is dangerous for the refrigerant to stay in a high-pressure state.
So, before moving into the evaporator coils, the refrigerant passes into the expansion valve so that it can release some pressure and cool down. By controlling the refrigerant flow rate, the expansion valve enables the evaporator to remove heat from your living space.
Expansion valves also work with other air conditioning components. In particular, your unit’s valve needs a functional thermostat so that it knows when to regulate its temperature by turning on or off.
Types of Expansion Valves
How does an air conditioner expansion valve work with newer technology? Modern air conditioner expansion valves come in different shapes and sizes, but the following types are still the primary choices:
Thermostatic Expansion Valve
Thermostatic expansion valves, or TEVs, use a mechanical valve to control an air conditioning unit’s refrigerant supply. They adjust in line with pressure changes, opening and closing depending on how much pressure they need to remove from the refrigerant. The valve uses an innovative sensor thermistor bulb to detect these temperature changes.
When an air conditioner’s evaporator kicks into high gear, the TEV springs into action, rapidly increasing the pressure flow rate. Then, as the pressure releases and the temperature declines, the valve slows the flow rate.
TEVs are the most common type of air conditioner expansion valve, offering a blend of simplicity and adaptability well-suited for portable units, window units, and larger air conditioning systems.
Unlike TEVs, float valves use tiny pieces called floats to control the ebb and flow of refrigerant. Each valve has two floats, a high and a low-side float.
- The low-side float rests inside the liquid refrigerant, keeping it at a consistent, solid level in the evaporator.
- The high-side float controls refrigerant levels within the condenser.
Part of what makes float valves a very popular choice among air conditioning manufacturers is the operation. These floats automatically detect low levels of liquid refrigerant based on their physical position, opening and closing as needed. They also prevent refrigerant backflow, protecting the evaporator from flooding.
Automatic Expansion Valve
Like TEVs and float valves, automatic expansion valves control how refrigerant flows from part to part within an air conditioning system. However, the mode of operation differs. Instead of using a mechanical valve or a float-based system, they use a diaphragm.
This diaphragm expands and contracts alongside pressure changes, opening and closing the valve as needed. However, these valves aren’t always reliable for air conditioners, as the diaphragm takes time and energy to cycle. Units that vary widely in pressure levels or swing back and forth won’t work well with automatic expansion valves.
Unlike other valves, a capillary tube, as the name implies, looks like a small tube-like cable. Usually placed at the top of a unit’s suction line, a capillary tube works best with an additional filter-drier piece to siphon off particulates. As the refrigerant passes through the long, narrow tube, it drops in pressure and temperature, effectively throttling it before it causes overheating or other problems.
Capillary tubes work best for outdoor units unburdened by space requirements. These tubes also don’t have any moving parts, so you can rest easy knowing that our cooling and heating repair team won’t have to fix them too frequently. Even if you have refrigerant issues, you can almost always rule out the capillary tube as the cause.
Why Are Expansion Valves Important?
How does an air conditioner expansion valve work to cool your home? The main purpose is to release the perfect amount of pressure to keep the refrigerant flowing. However, it’s important to consider factors beyond regulating pressure levels within a unit to appreciate the expansion valve’s role in your comfort levels.
Produce Cold Air
Expansion valves affect refrigerant pressure levels by absorbing heat, which is the only reason your unit can produce cold air. The valve connects the evaporator, which turns the liquid refrigerant into a gas, and the condenser, which returns the refrigerant to a liquid state. Without this link, there’s no way you can enjoy a perfect indoor temperature on demand.
Prevent Electrical Issues
Air conditioners need electricity to function, using countless wires, transistors, and other electrical components to power the cooling process. When expansion valves fail, the most common result is overheating. It puts strain on your system, making it work harder, which drives up energy bills and risks short-circuiting electrical parts or even small fires.
Common Signs of a Failing Expansion Valve
Detecting the signs of a failing expansion valve can prevent other air conditioning problems. So, if your unit’s struggling, checking its expansion valve is never a bad idea. Here’s what you might find:
It’s normal for air conditioning systems to make some noise, like a light humming or buzzing. However, whistles, squeaks, and other high-pitched sounds indicate a more serious problem, as failing or broken expansion valves will release pressure and sound similar to a kettle.
However, not all strange or loud noises occur because of a bad expansion valve. It could be one of the other parts making these sounds, like your unit’s compressor or fan. Still, you can effectively prevent these issues with regular maintenance from professionals like Georgia Air Cooling & Heating.
No Cool Air
Are your living spaces unusually warm? Do you hear your air conditioner running but notice a total lack of cold air coming out of the vents? If so, your unit’s expansion valve is likely malfunctioning.
While the expansion valve doesn’t directly control air temperature, it does control the cooling mechanism by allowing the unit’s refrigerant to move through the process. It effectively transforms warm, stolid air into that lovely breeze you feel when your air conditioner is working just right.
A failing expansion valve interrupts the process of changing the refrigerant from a liquid to a gas. However, not all cool air issues result from expansion valve problems. Broken fan motors, low refrigerant levels, and faulty thermostats also affect the way your unit handles its air supply.
All these parts depend on each other, so it is best to call for professional help as soon as you notice a problem. That way, you’ll avoid one part causing problems for several others.
If the refrigerant is like the blood that keeps the air conditioning system running, the compressor is your unit’s heart. It channels electric power to circulate refrigerant using a network of lines. When working properly, the compressor should automatically turn off once your living space reaches the set temperature or you manually shut it off.
Is your compressor running non-stop? This faulty operation can occur for many reasons, especially when there’s a broken expansion valve. The constant high-pressure levels force the compressor to work harder and harder, eventually causing irreversible damage.
Do you see blue, shiny liquid pooling outside your system? Is there freezing water or liquid in and around it? It’s almost certainly your unit’s refrigerant leaking.
The refrigerant should always remain inside your air conditioning unit. Leakage from the refrigerant lines will disable the cooling process as the lines rupture or break. This breakage could also be the result of a faulty expansion valve that causes a pressure buildup inside the refrigerant lines.
If your air conditioner has ruptures, cracks, or burst lines, you need to act quickly. Refrigerant can be a health hazard when mishandled, so contact local air conditioning experts like Georgia Air Cooling & Heating for safe solutions.
Choose Georgia Air Cooling & Heating
How does an air conditioner expansion valve work? Now you know. If you suspect that your unit has an expansion valve problem, relax and call the experts at Georgia Air Cooling & Heating for quick repairs, amazing customer service, and a competent team of specialists.Whether you’re interested in repairing or upgrading your AC unit, we can help—call Georgia Air Cooling & Heating at (912) 513-3724 today!