Car AC Expansion Valve Function, Symptoms, and Replacement Cost

Last Updated on June 24, 2019 by themechanic

The air conditioning expansion valve, which is better known as the Car AC expansion valve, is a component of the car air conditioning system that is found inside virtually every automobile. As you may know, refrigerant liquid circulates within the system and flows to the evaporator where it transforms into cool vapor. This is how cool air can come out of the air vents. The AC expansion valve is responsible for managing the flow of this fluid by reducing the pressure it receives from the AC compressor.

For instance, if too much refrigerant fluid reaches the evaporator, then the evaporator could potentially freeze. Alternatively, if the evaporator doesn’t receive enough refrigerant fluid, it could potentially overheat. This is where the AC expansion valve comes into play because it will know when the evaporator is freezing or overheated. Based on which one it is, the AC expansion valve will either restrict the flow of refrigerant to the evaporator or increase the flow. This ensures the air conditioning system keeps running smoothly without any setbacks.

5 Bad Symptoms

If the AC expansion valve ever malfunctions, certain symptoms will present themselves. These symptoms may not affect the performance of your vehicle itself, but they will certainly cause you and your other passengers to feel more uncomfortable. If you need to drive in hot environments, then you’ll want to seriously consider replacing your AC expansion valve.

Below are the top 5 symptoms of a bad car AC expansion valve.

1) AC Compressor Overly Active

When the AC expansion valve opens, it causes the AC compressor to pump refrigerant fluid into the system. Once the AC expansion valve closes, the AC compressor stops pumping fluid. But if you have a bad AC expansion valve, then it may not be able to close. As a result, the AC compressor won’t stop pumping fluid into the air conditioning system. This wears out the components of the system and causes the evaporator to get frozen.

2) Vent Frost

Sometimes a bad AC expansion valve may cause the air conditioner to generate excessively cold temperatures. This happens if the AC expansion valve allows too much refrigerant to go to the evaporator. Once that happens, frost will likely form on the air vents because the air is so cold.

3) Warm Air

One common symptom of a bad AC expansion valve is warm air blowing from the vents. This could also be due to other problems in the system, such as a bad AC compressor. But a bad AC expansion valve might prevent refrigerant from reaching the evaporator when it is needed. That is why warm air would come out in this case.

4) AC System Stays Off

It is possible that your entire air conditioning system will fail if your AC expansion valve stays open and never closes. With all that refrigerant getting pumped into the evaporator, the components of the system won’t be able to tolerate it for too long. Then you’ll end up having to replace all these components, if not the entire system itself.

5) Airflow Temperature Inconsistency

You’ll know the AC expansion valve is on the verge of failure when the air temperatures fluctuate between hot and cold. You may get cool air turning to warm air and then switch back to cool air again. This is a sign that your valve will soon fail if you don’t have it replaced.

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Replacement Cost

When the AC expansion valve goes bad, it’ll cost between $200 and $500 to replace it. The cost of the labor is around $100 to $300 while the cost of the parts is around $100 to $200. The total price may have fees and taxes added onto it as well. Try to shop around your local area to find the cheapest auto mechanic. Then perhaps you can cut those labor costs down a bit.

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