The A/C 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 A/C expansion valve controls the flow based on the temperature of the evaporator and the demand for cool air that is coming from the system.
How an A/C Expansion Valve Works
The A/C expansion valve manages this flow of refrigerant via a rod which exists inside of it. The rod can be moved either down or up, causing the passageway for the refrigerant to be either closed or opened; respectively.
If the passageway is opened, the refrigerant will be able to flow through. If it is closed, the refrigerant cannot flow through. When you set the air conditioner to a higher temperature, this causes more refrigerant to flow through the passageway. That is how the air is able to get colder.
When the flow of refrigerant is regulated, it is basically metered by the A/C expansion valve. In other words, the valve is calculating how much refrigerant must flow through the passageway based on the demands being placed onto it.
This not only includes when the driver sets a colder temperature, but also when the temperatures outside are naturally hotter. Anytime the heat resistance is greater in the surrounding environment, the air conditioner will need even more refrigerant to create a cool temperature in the cabin.
Bad Car A/C Expansion Valve 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 five common symptoms of a bad A/C expansion valve:
1) Warm Air From Vents
The most recognizable symptom of a bad A/C 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 like during the middle of August. 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.
Related: A/C Not Cooling? (Here’s Why)
2) 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 A/C expansion valve was not able to stop an overflow of refrigerant from entering the core.
3) A/C Compressor Always On
If your A/C 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.
4) Inconsistent Airflow
Sometimes a bad A/C 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 A/C expansion valve at once.
See Also: How to Clean a Clogged Cabin Air Filter
5) A/C 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 A/C expansion valve after this happens, you will also have to fix the other components that go bad too.
A/C Expansion Valve Replacement Cost
You will notice when the A/C expansion valve goes bad because your air conditioning system will ultimately stop functioning properly. It will either produce less cool air or it won’t produce any cool air at all. At this point, you will need to replace your A/C expansion valve to fix the problem.
The replacement cost of an A/C expansion valve is anywhere from $300 to $500. The parts cost itself will be between $70 and $150 while the labor costs will be between $150 and $350. If you want to reduce your expenses as much as possible, you should request quotes from the different auto repair shops in your area and see which one will give you the cheapest quote.