5 Symptoms of a Bad A/C Expansion Valve (And Replacement Cost)

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

how AC 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

air conditioning vent

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

air conditioning

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

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.


27 thoughts on “5 Symptoms of a Bad A/C Expansion Valve (And Replacement Cost)”

  1. my mechanic claims my leak was a cloud of what seemed like white smoke coming from the AC system and expansion vale, anyone have this problem ever? i thought it was a blown headgasket, alot of smoke supposedlyt came from this unit, was a green residue on the outside of it as well. was that ac coolant leak? from this valve?

    • I’d think coolant leak, check hoses. Happened to my old 96 honda civic, out of no where big cloud of white smoke looking but was vapor, looked under hood and saw heater hose really expanded, and all the coolant poured out. Cheap fix, think was $26, then refill coolant, and “burp” it before driving.

  2. My Camry 2001 ac tiny pipe is freeze and only the driver side is cold the passenger side is just air what can I do

  3. I’m told that the continuous humming noise coming from the dash during A/C operation is the A/C expansion valve. The blower motor has been proven not to make the humming noise. The noise only happens when the A/C is turned on. Is the expansion valve known to make a humming noise? I’m kinda skeptical about this diagnosis.

    • Thermal expansion valves do not not produce noise. What your most likely hearing is a blender door actuator motor out of calibration or a actuator motor broken off from a blender door. It could also be a foreign object that made it into the defroster vent down into the ac blender box and the airflow around it is making the sound. Check your in cab air filter. This is often not replaced and and if dirty restricts the intake of the air inside the car from going into the ac box under the dash to circulate the exchange of air.

      • Our expansion valve on a 2015 Hyundai Sonata is vibrating and making a horn sound. When it does that it stops cooling.

  4. My 2013 Hyundai Sonata ac is not working, I have change twice the compresor because the first compresor was having some electrical problems. I’m traveling to Atlanta Georgia and still have not Cold air just cool. I’m very frustrated I do t know what could be the problem anymore. Any thoughts? Please I can’t be investing any more

  5. Replaced compressor, evaporator, and expansion valve on 2010 camaro ss but when attempting to charge system the low side goes into vacuum.

    • That’s a restriction that could be caused by obstruction debris from a compressor failure and replacement or a malfunctioning thermal expansion valve.

  6. a small wire that is plugged into my ac refrigerant line (I think) has broken in two. What is that wire for? the AC doesn’t seem to be cooling and I didn’t know if that wire had anything to with it?

  7. I think I have bad expansion (txv) valve -2015 challenger, here are symptoms – fan speed hi.
    AC was working great, then a few days later drove it and it was weak at idle ( 63 deg vent) but cools when moving ( 45 deg). 90 deg air temp, at idle low side 50, high side 225. If i hose off condenser high side drops to 180, low side doesn’t move. Per the Chiltons manual, those pressures are in allowable range, i followed their directions and i freeze sprayed the bulb on TXV valve and low side didn’t move, it is supposed to drop 10 deg. The low pressure line doesn’t get cold. The temp is same for both passenger and driver vents, a dual zone system, so i don’t think blend door issue. I don’t think it is low on freon. I don’t think compressor is bad, i think TXV valve is maintaining low side at 50 instead of 35-40.

  8. I have a 2007 Chevy Monte Carlo and the A/C wasn’t blowing cold/cold, just ambient to cold air; also when I stop at a red light or parked my car the A/C would turn completely off. I took it to Brake Masters and they said it was a bad condenser. After paying $800 my car STILL has the exact SAME problem. I took it back and now the are saying it needs a new compressor… Can anyone help?

  9. Toyota Camry Hybrid 2009- dealership service department said my expansion block/valve was bad and they quoted 1400$ to fix it. That seems absurd. Especially based on what I’m seeing online. Any insights?

  10. I have no cold air at all from the a/c in the vehicle. Before attempting to do anything, with the car not running, I put a gage on the low pressure side on a very hot day and it reads 150. When I start the car and the air, the clutch pulls in and turns and the pressure goes to 80. I felt both the low side and high side lines and they seem to be about the same temp. (not hot, not cold). Is this a sign of a bad compressor?

  11. Hello, I have a recent failure on my A/C. After performing a service to detect leaks, the evaporator had to be replaced, after then the system started to fail. The system apparently works fine, cooling de air nice, but from time to time the air stops being cooled, instead it warms up a little bit but the compressor doesn’t disengage and the low pressure raises up to up to 90 psi, I have to turn it OFF and then ON for it to reset and start working again. Unfortunately I had to take it out of the shop because it was repaired when I was on the road and as next step they wanted to replace the compressor, which I thought they were guessing to fix it. Might it be because of a failure of the expansion valve ?

  12. 2008 hyundai tiburon v6; a/c started blowing hot air took to local shop fixed it or so we thought; out of freon! weel later no a/c took back schrader valve[s] leaking, fixed that ran for 48 hourss! no a/c wife is upset where be logical point for leaks?

    • Refrigerant is often colored with a bright dye. If you pop the hood and look around the A/C lines, you may be able to spot right away where the leak came from. The local shop should’ve tested for leaks before recharging the system.

  13. Have a 2013 Buick lacrosse hybrid but the AC system is not electrically controlled so it is like a normal Ac system… Low pressure reads 10 psi while high pressure reads 85 psi. Blowing hot air no matter what… Should I change the expansion valve?

      • 2004 Saturn Vue v6 the AC is fully charged just have that done completely now it only blows cold air when the engine is running it over 2000 RPM when you come to a stop light it starts blowing warm air don’t know if it’s expansion valve the compressor or the evaporator

  14. We have a 1996 Honda Civic, base model, that we saved for our son’s first car. 260k miles. It is a functional commuter for around town. The electromagnet coil of the AC clutch failed. We replaced it. After several months here head a metallic squealing sound and we thought we may have too much should thickness and that the clutch may be slipping. So we decided that we would remove all of the shims and tighten the clutch plate down so that it was always mechanically engaged and always spinning the compressor:s shaft. Other than reduced feel economy and extra wear on ac components due to the fact that the compressor is always spinning, could this cause any problem? Like an over-pressure situation?

    • I wouldn’t leave it fully engaged like that. You could freeze the lines from running it really cold and damage the A/C system. As for the squealing, I would check the accessory belt to make sure it’s not old and cracked. Make sure you’ve set the tension properly as well.

    • Hi Aiah. We do not have a shop, so unfortunately we can’t expand. However we hope the advice on this site proves useful to you if you plan on doing work yourself, or eases the diagnostic process if you end up taking your vehicle to a local mechanic.


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