Car AC Expansion Valve Functions, Symptoms, and Replacement Cost

Air conditioning is essential for the comfort of every trip you take in your vehicle, particularly in parts of the world where the weather is hot for a greater portion of the year. Yet many people do not understand how it functions, leaving them with expensive car repair costs. Learning about what a valve does and their common failure symptoms will help you to keep costs down when it’s time to replace them.

Car AC Expansion Valve Functions

The main function is to remove pressure from the liquid refrigerant in the system. This allows for expansion, and then converts the refrigerant from liquid to vapor inside the evaporator.  And also controlling the refrigerant flow, called metering. Inside of the valve is a moveable rod that moves up and down. This enables it to open and close the passageway inside, allowing refrigerant to enter, or not. At any given time it can accurately meter the precise amount of refrigerant that’s needed. As you know, some days it’s hotter than others, so this control is needed to adjust the AC, otherwise you’re going to be too uncomfortable in your car.

In fact, failure of the expansion valves is one of the top reasons that your AC has stopped functioning well, as they do wear out over time.

Car AC Expansion Valve Failure Symptoms

Generally, the first time you get a clue that something is wrong with your AC is through AC expansion valve failure symptoms. That first symptom is often with your AC blowing warm air, instead of cool. There may also be frost on the AC evaporator, or it may form on the vents.

Another indicator is when your AC compressor is constantly running. This is because the expansion valve will get stuck and fail to open. This means that the compressor will continue to pump refrigerant into the AC’s system, even when you already feel cold.

At this point, it’s recommended to take your vehicle to a vehicle air conditioning place to have it repaired. Unfortunately, the valves are often deep within your vehicle’s AC system and it’s not as simple as opening a door and putting gas in your vehicle.

Read also: Automatic Transmission Valve Body Functions and Failure Symptoms

Car AC Expansion Valve Replacement Cost

Usually car AC expansion valve replacement costs can start at about $100 and up to $150. You can expect to have a few hundred dollars in labour added to the total cost, so it’s essential to get quotes first.

Now that you understand what can go wrong with your car’s AC expansion valve functions you can get straight to business and ask auto repair shops exactly what the costs are, instead of paying for expensive labour to “discover” what is wrong with your AC.


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