5 Symptoms of Bad AC Expansion Valve & Replacement Cost

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bad expansion valve

If your car’s AC system is not performing as well as it used to, the a/c expansion valve may be the culprit. This component is responsible for regulating the flow of refrigerant into the evaporator, and when it fails, your car’s AC will not work properly.

In this article, we will discuss the symptoms of a bad expansion valve and outline the causes of its failure. We will also provide information on replacement costs and how to find a reputable mechanic.

How Does the Air Conditioning System of a Car Work?

The AC system in your car contains four main components- the compressor, condenser, expansion valve, and ac evaporator. The compressor is located near the engine, and it pumps refrigerant gas to the other two components.

The refrigerant passes through the condenser, a heat exchanger located in front of the radiator. Here, the heat from the engine is transferred to the refrigerant, which causes it to turn from a gas into a liquid.

The liquid refrigerant then passes through the valve and enters the evaporator. The evaporator is located in the passenger compartment, and it contains many small fins that help to dissipate heat. As the liquid refrigerant absorbs heat from the air inside the car, it evaporates and turns into a gas.

This process is then repeated over and over again until you shut off your AC system or turn down its temperature setting.

What Does the Expansion Valve Do?

The a/c expansion valve is a component that controls the flow of refrigerant into the evaporator. It prevents over-expansion and maintains pressure in the system by opening when needed to allow for more expansion or closing if there isn’t any expansion occurring at all times.

Symptoms of a Bad Expansion Valve

Following are the major symptoms of a failing expansion valve:

1. AC System Blowing Warm Air

One of the most common expansion control device failure symptoms is that your car’s AC system will only blow warm air instead of cold air. This can be caused by various issues, including low refrigerant levels or a leaking valve. If system operating pressures are below normal gauge readings, you must immediately notice.

If the air coming out of your ac is warm, you should have your valve checked by a mechanic as soon as possible. Low refrigerant levels can often be fixed by adding more Freon into the system, but if your valve is leaking, you will need to replace it before adding any more refrigerant.

2. AC Compressor Constantly Running

Another common symptom of a bad expansion valve is that the AC compressor will constantly run. This can be caused by low refrigerant levels, which will put extra strain on the compressor, or by a leaking valve, which will not allow the refrigerant to enter the evaporator properly.

If your AC compressor is running all the time, it is a sign that something is wrong with your valve and you should have it checked by a mechanic.

3. Inconsistent Air Flow

The airflow of your vehicle’s air conditioner becomes inconsistent when the ac expansion valve goes bad. The best way to tell if this is happening is by listening for changes in the blower motor running tone. If you hear a “chugging” sound as the revs drop then rise again, that may indicate that your expansion valve has failed.

If there are no obvious sounds coming from the engine bay, you can get an idea of whether or not your valve is bad by checking the ac system for leaks. If you find one, try tightening the fitting with a wrench and see if that stops it. If not, then chances are it’s time to get a replacement.

4. AC System Performing Worse Than

When the expansion valve goes bad, your car’s air conditioner starts performing worse. When the valve goes bad, it starts leaking freon into the atmosphere. The ac evaporator then needs to put more freon in the evaporator inlet to achieve the cooling effect and this causes the ac to overheat and perform poorly.

The symptom you will usually notice is that your car’s air conditioner will lose performance and start blowing warm air instead of cold air when everything else seems to be working fine.

5. Frost on Vehicle’s AC Vents & Orifice Tube

If you have a bad expansion valve, the expansion tube will start to frost over. When the valve leaks, it causes the refrigerant to overflow and mix with the compressor oil. When this mixture accumulates on the expansion orifice tube, it will freeze and cause frost to form.

If you see frost on your expansion tube, it is a sign that you have a valve problem and should get it fixed before any further damage occurs.

Causes of A/C Expansion Valve Malfunction

A/C expansion valve malfunction can be caused due to a number of reasons. Some of those have been discussed above, and some have been described explicitly in this section.

1. Blocked Expansion Device

The expansion valve is the key component of an A/C system. It not only controls the expansion and contraction of refrigerants but also acts as a filter to prevent debris from entering your vehicle’s air conditioning system. If dirt or other foreign objects get stuck inside this expansion device, it will cause clogging problems, leading to an expansion valve malfunction.

It is important to keep the valve clean and free of any obstruction to prevent this. Always use compressed air to blow out any dirt or debris accumulated inside the device.

2. Too Much Refrigerant Flow

An expansion valve malfunction can also be caused by too much refrigerant flow in your vehicle’s air conditioning system. This is because the expansion device has a limited capacity and cannot handle excessive coolant. If you notice that your valve is leaking, it might be due to overfilling or underfilling it with the right amount of refrigerant.

To prevent this, it is important to consult with a professional and properly charge your valve with the right amount of refrigerant. You should also never open or close the expansion device’s valves unnecessarily as that can cause damage and affect its performance.

3. Compressor Failure

The expansion valve can also malfunction due to a problem with the compressor. If the compressor fails, it will not be able to send enough refrigerant to the expansion device, and this will cause pressure problems which can lead to a valve leak.

If you are experiencing these types of problems, it is likely that you need a new compressor and should consult with a professional to have it replaced.

4. Improper working conditions

The expansion valve can also malfunction due to improper working conditions. This might include operating the vehicle in very high or low temperatures, driving through water puddles, or even using an aftermarket valve that is not compatible with your car’s ac system.

To prevent this, it is important to always use the correct valve for the make and model of the vehicle and maintain it properly. You should also never drive through water puddles or operate your valve when it has been sitting idle for a long time without being used at all because this can cause damage to its internal components, which may result in an expansion valve malfunction.

Expansion Valve Replacement Cost

The expansion valve replacement cost varies depending on the make, model and year of your vehicle. In some cases, it can be as low as $200, while in other instances, it may exceed $500 or even more. The easiest way to find out how much an expansion valve for a specific car would cost is by going online and searching for the valve replacement costs for that particular make and model.

You can also contact your local auto parts store to inquire about the valves. They will likely have several different expansion devices in stock, so it is a good idea to take some time browsing through their inventory before making any final decisions on which one you want to buy.

If you find that the expansion valve replacement cost is too expensive for you, consider purchasing a used expansion device from an auto parts store or salvage yard.


The expansion valve is a small part of your vehicle’s ac system that plays an important role in its ability to cool down the air. If you are experiencing problems with your expansion device, it might be due to the reasons mentioned above. In some cases, replacing this expansion valve will resolve those issues but not always, so you should consult with an ac system specialist before making any final decisions on what to do next.

You can also consider having your valve professionally serviced by a mechanic or auto parts store, but this option may be expensive so make sure it’s worth it!

Frequently Asked Question

How do you test an expansion valve?

Testing an a/c expansion valve is not a difficult process and can be done with a few simple tools. All you need is a screwdriver, some pliers, and a digital multimeter.

The first step is to remove the expansion valve from the car’s ac system. This can usually be done by unscrewing it from the compressor or using pliers to pull it out.

Next, you’ll need to use a screwdriver in order to pry open the expansion valve’s cap and inspect its internal parts for signs of wear or damage such as cracks on the piston inside the expansion device (which would indicate that there is an air leak). If everything looks okay then all you have left to do is reconnect everything back together again and start driving around!

How do you unclog an expansion valve?

If you think your ac expansion valve might be clogged, there are a few methods you can try to clear it out. One is to use compressed air and blow the obstruction out from the other side. Another option is to pour vinegar or bleach into the expansion valve in order to dissolve any built-up sludge or dirt inside.

How do I know if my a/c expansion valve is stuck open?

One common symptom of a stuck expansion valve is when the air conditioning unit starts to run continuously, even when the car isn’t being driven. This usually indicates that there is something blocking the flow of refrigerant which is causing the expansion valve to remain open.

Where is the A/C expansion valve located?

The expansion valve is located in the ac system between the compressor and condenser. It is usually attached to a metal bar or tube that runs across these two components, although some expansion valves have their own dedicated mounting bracket.

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