How to Tell if There’s an Issue With Your A/C Expansion Valve

The A/C expansion valve is a vital part of a vehicle’s air conditioning system because it is responsible for the amount of refrigerant liquid that flows throughout the system. When there’s too much refrigerant, the evaporator will get too cold and freeze, and the same issue happens when it’s too hot, which will then cause the evaporator to overheat. 

The A/C valve prevents either of the two situations from happening, which is why it should always be in optimal condition. In this article, we will share how to determine the symptoms of a bad expansion valve so that you can address the problem before things get worse. 

How It Works

First, you need to know how an A/C valve works. As mentioned, it manages the refrigerant flow through a rod inside of it. You can either move the rod up or down, which will then close or open the passageway of the refrigerant. If it’s open, the refrigerant will be able to flow, while it won’t be able to if it’s closed. 

When the AC system is set to a higher temperature, it will cause more refrigerant to flow through the passageway, so it will get colder. This also includes the outside temperature. If it’s hotter outside, the AC will need more refrigerant to create a cool temperature inside the vehicle. 

With that said, the A/C expansion valve calculates the amount of refrigerant that should go through the passageway based on the demands. 

Now, what are the signs of a bad A/C expansion valve? 

  • Warm air coming from the vents: This is a popular sign that something’s wrong with the A/C expansion valve. When you turn on your car’s air conditioning system, and it blows warm air, it means that there’s not enough refrigerant that is going through the passageway. 
  • Frost on vents: Your car’s cold temperature should just be enough, but when it forms frost on the vents, this means that the evaporator is likely freezing. This isn’t a good thing because this can damage the overall performance of your unit. 
  • A/C compression not shutting correctly: When your A/C compressor is always on and doesn’t shut properly, the compressor will just keep on pumping refrigerant, which will put more stress on the compressor. When this happens, other parts of the system will be affected and eventually fail. 
  • Inconsistent airflow: This is when the air coming out of the vent is either too warm or too cold. Most of the time, the air will alternate back and forth between different temperatures at different times. 

If you recognize these signs and don’t address them immediately, you could end up with an A/C system failure. When this happens, the vital parts of your air conditioner will be damaged, which will lead to more expenses and headaches. A replacement will not work for this, but will also be required to replace the other affected components. 


Don’t let this happen to your vehicle. Instead, commit to preventative maintenance to ensure that your AC system remains in good condition. You don’t want to spend a lot of money just to have it repaired, right? For this reason, keep an eye out for the signs mentioned above because prevention is always better than a cure! 

Let us take care of your mobile fleet services in Ontario at Simplicity Air. You can reduce expensive downtime with our help through our 34-point inspection. Book a fleet check with us today!