Essential Guide to Aircon Expansion Valve

Sadly, many homeowners are not aware of the importance of their air conditioner’s expansion valve. Properly functioning valves can ensure that your AC system is operating at peak efficiency and also protect you from costly repairs in the future.

This blog post will discuss what an expansion valve does, how to identify a faulty valve, and what to do if it malfunctions.

What Is an Aircon Expansion Valve?

Expansion valves are among the most crucial parts of any type of air conditioning unit. This device controls refrigerant flow inside the refrigeration system.

They assist by facilitating the changes that occur of liquid higher-pressure refrigerant in a condensing unit into a gas lower pressure refrigerant inside the evaporator.

How Does an AC Expansion Valve Work?

To understand how expansion valves work in an AC system, it becomes important to gain a basic understanding which relates to the direct relationship that occurs between pressure and temperature. When refrigerant pressure starts to increase, the temperature also starts to rise. The increase in pressure and temperature is what occurs as the refrigerant starts flowing through a compressor.

Expansion valves are typically installed at the inlet of the evaporator and work with an orifice tube that regulates the refrigerant flow through the AC system’s vehicle. If the refrigerant flow is too high, it will cause the evaporator coil to freeze over, while too little refrigerant flow will cause the evaporator to overheat, which will compromise the overall efficiency of your AC system.

The expansion valve will meter the refrigerant flow based on the temperature of the evaporator and the cooling and load demand of an AC system.

Related Read: How does an air conditioner works?

Expansion Valve Types

Thermostatic Expansion Valve

The TEV (thermostatic expansion valve) uses a valve mechanism that controls the flow of liquid refrigerant into an evaporator coil. From here, the evaporator controls the flow according to its pressure. These devices still operate well even over various fluctuations, making them the most suitable for use in AC systems.

As soon as the evaporator starts warming up, this valve increases the flow rate. Once it has cooled down, the rate will be slowed down. There is also a sensor thermistor bulb that will detect the temperature of the coil.

Automatic Expansion Valve

This expansion valve uses a pressure-actuated diaphragm used to regulate the flow of refrigerant from the “liquid line” into the evaporator. The one drawback about these expansion valves is that they can become counterproductive when the load fluctuates. This type of valve is not suitable for use in an air conditioner since the load usually fluctuates a lot, especially when you turn your AC on and off. 

Float Valve

These valves operate with the use of a float that is immersed in the refrigerant when in liquid form. To control refrigerant flow, both high-side and low-side floats will be used. The low-side works by ensuring the liquid refrigerant stay at a constant level in the evaporator.

When the liquid runs out, it will open and then close as soon as new liquid flows in. The high-side float is situated on the high-pressure side of the system and makes sure the refrigerant maintains constant levels inside the condenser.

Once the compressor starts working, the float chamber receives the condensed refrigerant, which causes the valve to open. Once the liquid levels inside the float chamber start going down, the opening of the valve will close. During these processes, the liquid won’t be able to flow back into the evaporator.

Capillary Tube

This is a type of tube that features a small internal diameter. It is typically installed at the suction line and is also coiled due to its length. To remove moisture and dirt from the refrigerant, a filter-drier is usually installed at the entrance of the tube. To make sure the device is performing well, the refrigerant inside the system should be correctly calibrated according to its “factory level”. When compared to thermal expansion valves or TEV/TXV, these capillary tubes are typically cheaper and more commonly used in window or room air conditioners.

Where Is the Expansion Valve Located?

The expansion valve is located in the “liquid line” between the inlet of an evaporator and the condenser. It functions on the other side of a system relative to a compressor in the AC system.

Are There Any Symptoms for A Bad Expansion Valve?

The most obvious symptom is that the expansion valve is no longer working or not performing the way it should is when an AC starts blowing out warm air. This usually means that the flow of refrigerant is restricted, which means it is unable to flow into the evaporator core.

How Long Do Expansion Valves Last?

It generally has to do with wear and tear. If you use your AC unit all the time, the faster it will start wearing down.

What’s Next?

So maybe you don’t know what an expansion valve is, and that’s okay. We can help! Contact our team of experts if you need any help understanding how your AC system works, and the various AC parts or have questions about the best way to maintain it, so it lasts for years and keeps cooling your home properly.

Last Updated on

Leave a Comment

Your email address will not be published. Required fields are marked *