5 Symptoms of a Bad Car AC Expansion Valve


The AC expansion valve is found within the air conditioning system of a vehicle. The purpose of the valve is to manage how much refrigerant liquid can flow throughout this system. Whenever there is an abundance of refrigerant, the core of the evaporator will get too cold and eventually freeze. Just like if there was not enough refrigerant, the core would get too hot and then overheat. To prevent either scenario from happening, the AC expansion valve controls the flow based on the temperature of the evaporator and the demand for cool air that is coming from the system.

5 Bad Symptoms

When you have an expansion valve that stops working properly, the symptoms will show up quickly. These symptoms will mostly pertain to the functionality of the air conditioning system. If it is a hot summer day and you turn on your air conditioning system, you will notice something is wrong if you’re not getting the cold air that you’re expecting.

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

Warm Air – The most recognizable symptom of a bad AC expansion valve is when you turn on your air conditioner and warm air starts blowing out of the vents. This would obviously mean that not enough refrigerant is making its way to the core of the evaporator. Most people will discover this problem at the worst possible time when it is hot outside. You should always test your air conditioner in the months before summertime approaches. That way, you will be ready for this problem ahead of time.

Frost on the Vents – A car’s air conditioner should never be cold enough to the point where frost forms on the vents. If you have frosty vents in your vehicle, this is an indication that your evaporator is freezing. The air that comes out of the vents will also be a lot colder than normal. You may think this would be a good thing, but it will actually damage the overall performance of the system if it continues on like this. Obviously, in this situation, the AC expansion valve was not able to stop an overflow of refrigerant from entering the core.

AC Compressor Always On – If your AC expansion valve stays open and cannot shut properly, this is how refrigerant continuously gets pumped into the air conditioning system. The compressor will just keep on pumping this refrigerant without ever stopping. The more that this goes on, the more stress that is placed on the compressor. Once that happens, other components within the air conditioning system will start to wear down and fail.

Inconsistent Airflow – Sometimes a bad AC expansion valve will provide an inconsistent performance in its ability to regulate the flow of refrigerant throughout the system. If this were to occur, the air coming out of the vent may be too cold or too warm. The air will likely alternate back and forth between different temperatures at various times. People may mistakenly think the system is fine and that it just needs a few minutes to fix itself. However, if the air ever goes from cool back to warm again, then inspect the AC expansion valve at once.

Read also: 5 Tips to Keep Your Car Starter Motor Durable

AC System Failure – If you are experiencing any of the symptoms on this list but you continue to ignore them, it will eventually result in your entire air conditioning system failing. In other words, some of the vital components of the air conditioner will be damaged. Even if you replace the AC expansion valve after this happens, you will also have to fix the other components that go bad too.


1 comment

  1. Sariah Meagle 15 February, 2019 at 07:54 Reply

    Probably the frost on my husband’s truck’s vents could be a cause for concern to have his air conditioner expansion valve repaired. Since he’s been complaining of an inconsistent airflow inside the truck, it could be a sign that it needs to be fixed. I’ll tell him to go to an auto service if he notices that the air conditioner has been blasting warm air for no reason at all.

Leave a reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.