Aircon Expansion Valve Guide

Comprehensive Guide to the AC Blower Motor
23/07/2021

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Unfortunately, many homeowners do not realize how important the expansion valve on their air conditioners is. When this valve functions properly, it can help to ensure your AC will operate at its peak efficiency and protect it against future expensive repairs. In this article, we will discuss what expansion valves do, how to identify a faulty valve, and what you should do if they malfunction.

What are Aircon Expansion Valves?

One of the most critical components of any air conditioner is the expansion valves. They control the flow of the refrigerant inside the AC system.

They help facilitate the changes that happen in a high-pressure liquid refrigerant inside a condensing unit being transformed into a lower pressure gas refrigerant within the evaporator.

Related read: Overview of AC Parts

How Do AC Expansion Valves Work?

To understand the way expansion valves operate inside of an AC system, it is important to have a basic understanding of the direct relationship between temperature and pressure. The temperature begins to rise whenever refrigerant pressure begins to increase. The increase in temperature and pressure is what happens when the refrigerant starts to flow through the compressor.

Typically expansion valves are installed on the evaporator inlet and work with orifice tubes that regulate the flow of refrigerant through the vehicle of the AC system. Too high of a refrigerant flow can result in the evaporator core freezing over. On the other hand, the evaporator can overheat when the refrigerant flow is too low, which can compromise your AC system’s overall efficiency.

The expansion valve meets the refrigerant flow based on the evaporator’s temperature and the AC system’s load demand and cooling.

Types of Expansion Valves

Thermostatic Expansion Valve

There is a valve mechanism used by the thermostatic expansion valve (TEV) to control the liquid refrigerant flow to the evaporator coil. The evaporator then controls the flow based on its pressure. Even over different variations, the devices will still operate, making them well0suite to use in an AC system.

When the evaporator begins to warm up, the flow rate will be increased by the valve. After it cools down, this rate slows down. The sensor thermistor bulb also detects the coil’s temperature.

Automatic Expansion Valve

The expansion valve uses a pressure-actuated diaphragm to regulate the refrigerant flow from the liquid line to the evaporator. One drawback to this type of expansion valve is whenever the load fluctuates; it can be counterproductive. This kind of valve is not well-suited to use in air conditioners since usually, the load fluctuates quite a bit, especially when turning your AC off and on.

Float Valve

This type of valve works by using a float immersed inside the refrigerant in liquid form. To control the flow of refrigerant, both low-side and high-side floats are used. Low-side floats work to ensure the liquid refrigerant remains at a constant level inside the evaporator.

Once the liquid has run out, it opens and then closes just as soon as new liquid flows in. The high-side float is located on the system’s high-pressure side and ensures that constant refrigerant levels are maintained inside the condenser.

After the compressor begins to work, the condensed refrigerant is received by the float chamber, causing the valve to open up. After the liquid level within the float chamber begins to go down, the valve opening will close. During those processes, the liquid will be unable to flow back to the evaporator.

Capillary Tube

This kind of tube has a small internal diameter. Typically, it is installed on the suction line. Due to the length, it is also coiled. To remove dirt and moisture from the refrigerant, usually, a filter-drier is installed at the tube’s entrance. To ensure that the device is performing properly, the refrigerant within the system needs to be calibrated correctly based on its factory level. Compared to TEV/TXV or thermal expansion valves, typically capillary tubes are less expensive and more commonly used in-room or window air conditioners.

Where are Expansion Valves Located?

These expansion valves are found on the liquid line between the condenser and the evaporator inlet. It works on the opposite side of the system in relation to the AC system’s compressor.

What Are the Symptoms Of Bad Expansion Valves?

Of course, the most obvious symptom of all is when the expansion valve is not working any longer or not performing the way it is supposed to when an AC starts to blow warm air out. Usually, that means the refrigerant flow is restricted, meaning it cannot flow to the evaporator core.

How Long Does an Expansion Valve Last?

Usually, it depends on the amount of wear and tear. If your AC unit is used constantly, it will begin to wear down.

What Is Next?

Perhaps you don’t know what expansion valves are. That is fine. We are here to help you. Call the experts on our team if you need assistance in understanding how your air conditioning system works or if you have any questions about how to maintain it best so that it lasts for many years and continues to cool down your home properly.

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