Is your car’s air conditioning blowing warm air or failing to cool the inside of your car? The problem might be a faulty A/C expansion valve.
Read on as we go over the most common symptoms of a faulty A/C expansion valve, what causes it to fail, and what you can expect in terms of replacement costs.
Purpose of an A/C Expansion Valve
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 It 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 signs will become apparent quickly, especially on a hot summer day. Here are the most 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.
6) Loud Noises from the A/C System
A failing expansion valve can cause unusual noises, such as rattling, hissing, or whistling sounds, coming from the A/C system when it’s running. These noises may be more noticeable when the system is first turned on or while you’re accelerating.
The sounds can be caused by the valve not opening or closing properly, or by debris trapped within the valve. If you simply ignore the problem, these noises can indicate a worsening problem that may lead to more extensive damage to the A/C system.
7) Moisture or Refrigerant Leaks
A damaged expansion valve may allow refrigerant to leak, which can lead to visible moisture or oily residue around the A/C components or puddling under the vehicle.
The expansion valve has seals that can deteriorate over time, causing refrigerant to escape. In some cases, a malfunctioning expansion valve may also cause the system to operate at incorrect pressures, putting stress on other components and potentially causing leaks elsewhere in the system.
If you notice any signs of leaks, such as puddles under your vehicle or a persistent loss of cooling performance, get your air conditioning system inspected and repaired promptly. Leaking refrigerant is not only bad for your vehicle, it’s bad for the environment.
A/C Expansion Valve Replacement Cost
We recommend Parts Geek for the best prices and selection.
The replacement cost of an A/C expansion valve is typically in the range of $200 to $500 (parts and labor). The valve itself will be between $50 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 make sure the shop you go with is ultimately in line as far as price is concerned.
But don’t go off of price alone as the quality of work (and parts) makes a huge difference.
What Causes the A/C Expansion Valve to Fail?
Several factors can contribute to the failure of an A/C expansion valve. The most common causes of A/C expansion valve failure include:
- Contamination: Debris, moisture, and other contaminants can clog the valve or damage its seals, causing malfunction or leaks.
- Age and Wear: Like other mechanical parts, over time, the valve’s internal components can deteriorate, affecting its ability to regulate refrigerant flow accurately.
- Incorrect Refrigerant Charge: Overcharging or undercharging the system can cause the valve to stick open or closed, leading to poor performance and potential damage.
- Improper Installation: Incorrect installation during repair or replacement can result in leaks, improper refrigerant flow, or valve damage.
- Overheating: Excessive heat within the A/C system, caused by issues like a malfunctioning condenser fan or clogged condenser, can damage the valve’s seals and internal components.
- Car Making a Humming Noise While Driving? (7 Causes and Cost to Fix) - December 10, 2024
- 7 Reasons Your Steering Wheel Shakes (at Low and High Speeds) - December 9, 2024
- 7 Symptoms of a Bad Timing Chain Tensioner (And Replacement Cost) - December 4, 2024
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.
Probably a/c dye.
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
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.
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
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.
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?
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.
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 $800 my car STILL has the exact SAME problem. I took it back and now the are saying it needs a new compressor… Can anyone help?
Toyota Camry Hybrid 2009- dealership service department said my expansion block/valve was bad and they quoted 1400$ to fix it. That seems absurd. Especially based on what I’m seeing online. Any insights?
That does seem high. Is that all they quoted you for?
If it’s designed like my toyota tundra, they’ll pull your entire dashboard to change it. Ridiculous design. It’s a lot of labor cost to pull a dashboard.
Well, that would definitely do it. $1400 doesn’t seem so bad now…
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?
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 ?
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.
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?
I’d bring it to a shop to have it looked at. It may need a recharge or there could be something else going on.
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
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.
Pls can you expand you business in country Sierra Leone?
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.