Why doesn’t my AC work in my car? This is somewhat a broad question, as the AC system can fail in different ways. But don’t worry, we’ll discuss all of them in this post. And we’ll help you find the solution to your problem, as well as the costs:
Why Doesn’t My AC Work In My Car: How It Works
First, the basics of car air-conditioning. Learning how the system works will help you understand how the problem occurs. Of course, you can skip this section if you already have a basic understanding of how the system works.
The car’s air-conditioning system has five major components, working together to use refrigerant to make cool air. Here’s how they work:
- It starts with the compressor, which turns on when you switch the air-conditioning system on. The engine’s drive belt is what powers the compressor.
- When the compressor turns on, it compresses the refrigerant to turn it into a high-temperature and high-pressure gas.
- The gaseous refrigerant then travels into the condenser to remove the heat and lowers the pressure of the refrigerant. This process transforms the refrigerant into a liquid. Additionally, there’s a dryer that removes any remaining gas.
- Afterward, the liquid refrigerant travels into an expansion valve. This transforms it back into a high-pressure gas and further reduces its temperature. At this point, the refrigerant is at around 32º F.
- The refrigerant travels through the evaporator, where a blower motor will blow air through the evaporator. The result becomes cold, and the air is blown into the car’s cabin.
- Finally, the refrigerant travels back into the compressor to repeat the process.
If you’re more of a visual learner, we recommend watching the video above to get an understanding of how the system works. The system is the same in any car, including electric cars. Although the compressor in EVs works by using the battery since there’s no drive belt.
Why Doesn’t My AC Work In My Car: How Car Heater Works
Note that the heater in cars is a different system. Car heaters work by circulating the hot coolant in your car to a heater core. How does it work? As you probably know, a car engine uses coolant to maintain optimum operating temperature.
Coolant is hot since it has to carry away the heat from the engine, its operating temperature is usually between 195º F to 220º F. When you turn on the heater in your car, the cooling system will redirect some of the hot coolants through the heater core before it enters the radiator to cool down.
A blower motor will then blow air through the heater core. And it results in hot air entering the cabin. That’s it, the heater in cars is fairly simple.
However, note that electric car heater works differently. It typically uses a heat pump to create hot air, powering it with electricity from its batteries. Now that you know how both systems work, let’s take a look at why your AC isn’t working:
Car AC Not Blowing Cold Air
As mentioned, “why doesn’t my AC work in my car?” is a bit of a broad question as the air-conditioning system can fail in several ways. The most common one is when the vents blow air but it isn’t cold. There are two scenarios here:
First, the AC is constantly blowing lukewarm air. Second, it’s doing so only when the car is stationary. In other words, the AC works only when driving.
Why Doesn’t My AC Work In My Car: Potential Causes
If none of those two scenarios apply to you, then you can skip to the other sections. If it does apply to you, here are the potential causes:
- Broken compressor. A failing AC compressor will make a whining or growling noise when you turn on the AC. Additionally, the compressor should make a click or a switching noise when you turn the AC on. If you don’t hear that switching noise, then the compressor clutch has failed.
- Drive belt issues. As mentioned, the drive belt powers the compressor. If the belt fell off or is loose, then it won’t power the compressor.
- Damaged or clogged condenser. The condenser looks like a radiator, and if the fins are damaged or there’s dirt blocking it, then it won’t have sufficient airflow to cool the refrigerant. In the case of the latter, cleaning it with a coil cleaner will be sufficient.
- Faulty cooling fan. Most cars should have a fan behind the condenser, and it should immediately turn on when you turn on the AC. If it doesn’t turn on then the condenser won’t work optimally.
- Electrical issues. Such as with the fuse or wiring of the AC system.
- Overheating engine. The engine’s temperature can affect how cold the AC is. However, this usually only affects it if the car is stationary.
Why Doesn’t My AC Work In My Car: How To Diagnose
If your car’s AC works but only when driving, then you should check our article here. If that scenario fits you, you’ll find more information there. Otherwise, here’s how to do a diagnosis:
Essentially, what you need to do first is ensure that the fuse and electrical system are working fine. Once you’ve established those are fine, you can start diagnosing the components. This includes:
- Check the AC service ports to see if you have enough pressure and refrigerant inside the system. If not, then there’s a leak and you should skip to the next section to learn how to find it.
- Ensure the compressor isn’t making any loud noise and that the clutch is engaging. As mentioned, it should make a clicking/switching noise when you turn the AC on.
- Check the drive belt, it should have tension when you press on it. If it’s loose, you’ll need to tighten or possibly replace it.
- See if the condenser is damaged or blocked. Read our guide to condensers if you suspect that’s the culprit.
If one of those components is faulty or damaged, then you’ll need to replace it. But we’ll get into that in the repairs and costs section. Now, if you suspect you have a leak, here’s how to find it:
Why Doesn’t My AC Work In My Car: Diagnosing Refrigerant Leak
The AC system is a closed-loop system. Meaning that refrigerant only circulates inside it and isn’t supposed to escape. So, if you have low refrigerant, this means you have a leak somewhere and you’ll have to fix it. Ignoring the leak will cause premature damage to other AC components.
To find the leak, you’ll need to purchase a car refrigerant kit that has UV dye in it. Then you fill up your AC system with that, let it run, and then use UV light to detect the leaks. ChrisFix has a great video on this:
Note that the leak can take up to a month to spot if it’s a very small one. If you can’t find it upon first inspection, you’ll need to be patient and check it regularly.
Additionally, you shouldn’t use these refrigerant kits to refill your AC system after you fix the leak. They’re imprecise and will lead to further damage to your AC component. Always go to a professional technician with proper recovery, recycle, and recharge machines.
Heat Not Working In Car
As mentioned, the heater is technically a different system from the air-conditioning of your car. So the components at fault here are different, and here are the potential culprits:
- Low coolant. Check your coolant reservoir and see if it’s at the appropriate level – there’s a minimum and maximum marker on it. The system can’t flow coolant to the heater core if there’s not enough of it.
- Faulty thermostat. This device controls the flow of coolant in the system. If the bypass valve is stuck open, the coolant might not be able to get to operating temperature, resulting in air that’s barely warm when you turn the heater on.
- Leaking heater core. This allows coolant to escape and resulting in sub-optimal heater temperature.
- Do you have a bypassed heater core? Many people bypass their heater core when it’s leaking as a budget fix. Works great to prevent leakage, but that means your heater won’t work.
- Fuse or electrical issues that are preventing the heater controls from working properly.
The hardest one to diagnose is probably the thermostat issue. You’ll need to take it out of the thermostat housing, then submerge it in water with varying temperatures to see if the valves are opening correctly.
Since it can get quite complex, we recommend reading our guide to thermostat problems to learn more about troubleshooting. Note that if you have thermostat or coolant level issues, this will likely affect engine temperature as well and you should fix it before it damages the engine.
AC Fan Not Working
If no air—or very little air—is coming out of the vents in your car, then that means you have a blower motor issue. That’s the fan that draws in outside air and blows it into the cabin.
It’s very rare for the blower motor to stop working, but it can happen. In any case, if you think you have issues with the blower motor, here are the potential causes and how to troubleshoot them:
1. Blown Fuse
The first thing to check is your fuse box. Most cars have a fuse box in the engine bay, it’s a black plastic box that you can easily open by undoing a few clips. However, some cars have a fuse box in the cabin, so check with your owner’s manual if you’re having difficulties finding it.
After you locate the fuse box, open it and there should be a diagram inside the cover that tells you what the fuses are for. Find the fuse that controls the air-conditioning blower motor, and check if the fuse is in good condition.
You can visually inspect it. But a sure way to check is by using a test light, where you attach its lead to the negative battery terminal, and then touch the fuse’s pins.
If it doesn’t light up, then you have a blown fuse. Note that the fuse has to be plugged in to do this test. If you have a blown fuse, you can simply replace it. Most car fuses cost no more than $15, but some specialty fuses may cost up to $100. But if your fuse seems fine, then onto the next thing:
2. Clogged Cabin Filter
Your car’s blower motor may be fine, but you have a clogged cabin filter. They filter out dust and other pollutants from entering the cabin, ensuring the air in the cabin is clean.
They will eventually become clogged, just like any filter. And if the clog is bad enough, there will be less airflow coming out from the vents. Leading you to believe that there’s an issue with the blower motor.
Cabin air filters typically need changing every 15,000 to 30,000 miles. Although you might need to change it sooner if you live in a heavily-polluted area. In any case, you can visually inspect it.
You’ll need to consult with the service manual to find it, as the location varies depending on the make and model. Some are accessible from the engine bay, others require you to remove a few parts in the cabin to access it.
If it seems dirty, you’ll need to replace it which should cost no more than $50. If that doesn’t fix the problem, continue reading:
3. Bad Blower Motor Or Resistor
The blower motor has two main components: the motor itself and the resistor. The resistor is a bunch of coils that restrict electricity to control the fan speed of the motor.
If you see symptoms such as the fan only working at high speeds and/or there’s no change in fan speed when you adjust it, then you likely have a bad resistor but the blower motor itself is fine.
Meanwhile, if the fan doesn’t work at all or it works intermittently and you’ve checked the fuse, then you likely have a bad blower motor. If this is the case, you’re going to have to replace it.
Verifying this can be a bit of a hassle depending on the location of the blower motor in your car. But you can test the condition of your motor by using a multimeter to see if the electrical connections are still working properly. Watch the video above to learn how.
Why Doesn’t My AC Work In My Car: Repairs And Costs
There’s quite a lot to cover here, so let’s get into the potential repair costs. Starting with the estimates if your AC isn’t blowing cold air:
- Compressor replacement is around $850 on average. Likely more in luxury cars.
- Drive belt replacement is usually around $150 to $200. However, if you need to replace the tensioner then it’s around $250.
- AC condenser replacement usually costs between $600 and $700. If you only need to change the cooling fan, that’s usually around $400.
- Replacing leaking AC lines varies greatly depending on the car’s make and model, as well as the extent of the leak. But expect it to cost somewhere around $650.
- Evaporator replacement is anywhere between $900 and $1,200. This is a very rare issue, but we thought it’d be good to mention just how expensive it can get.
- Wiring issues are anywhere between $200 to $400 depending on the extent of the damage.
Note that the estimates above include labor costs, but don’t include the cost of recharging your car’s refrigerant. And it will be necessary every time you do repairs on the AC system. This should cost no more than $150 for most cars.
Additionally, AC repairs are often difficult and time-consuming. If you’re not sure about your mechanical skills, it’s best to leave the job to professionals to avoid further complications that can add to the cost. In any case, we’ve linked the repairs to the appropriate articles so you can learn more about them.
Heater Repair Cost
Meanwhile, if your heater isn’t working, then here are the repairs you might need to do and their cost estimates:
- Refilling coolant should cost no more than $20 per gallon of coolant and you can easily do this by refilling it through the coolant reservoir. Note that you will need to find the leak to prevent further issues and the repair cost ranges between $200 to $1,500 depending on the cause.
- Replace the thermostat. This costs between $150 and $300 in most cars.
- Heater core replacement costs around $700. Most of it is labor since accessing the heater core is very difficult, the core itself is usually around $150.
- Wiring or electrical repairs are between $200 and $400 on average.
AC Fan Repair Cost
Finally, if no air is coming out of the vents, here are the repair cost estimates:
- Fuse replacement is typically no more than $15 and you can do it yourself. Cars rarely use specialty fuses for the AC system and blower motor.
- Cabin air filters are around $40 and you can replace them yourself as well. It’s around $85 with labor.
- Blower motors for cars cost around $350 to replace including labor. Meanwhile, the resistor is around $150 on average.
Unlike the other issues, this should be relatively cheap and easy to fix. Even replacing the blower motor can be a DIY job if there is no secondary damage such as fluid leaks or wiring damage.
Why Doesn’t My AC Work In My Car: FAQs
Got any more questions about the car air-conditioning system? You might find these answers helpful:
Which Car Company Was The First To Offer Air Conditioning In Its Cars
The first company to introduce air-conditioning in cars was the Packard Motor Car Company, an American luxury car company that went defunct in 1958. The 1940 Packard was the first car to have factory air-conditioning that was supplied by Bishop & Babcock Mfg. Co. from Cleveland. Before this, all air-conditioning in cars was either home-built or just experiments.
Why Is My AC Not Blowing Cold Air
There are many potential causes, but the most common ones are a faulty compressor, damaged condenser, and/or refrigerant leak causing low refrigerant.
How To Put Freon In Car
You can add freon or refrigerant by using a car AC refrigerant kit, which usually costs around $35. The process entails attaching it to the car’s low-pressure service port, setting the gauge according to the ambient temperature, and then refilling the system with the engine running until the gauge reaches the appropriate pressure. However, this isn’t recommended as it’s not accurate and can cause damage in the long run. It’s better to have a professional do it for you with the correct tools, which usually cost no more than $150.
How Much Does It Cost To Fix AC In Car
It depends on the cause. If your AC isn’t cold, the average cost is between $400 to $800. But sometimes it can be less or more than that. Meanwhile, heater issues can cost as much as $700 if you need to replace the heater core. And if there’s a leak, the cost can go up to $1,500. The cheapest repairs are usually with the fan or blower motor, which costs around $350 to replace in most cars.
Does The AC Use Gas
Air-conditioning system doesn’t use gasoline directly, but it does affect your engine’s fuel consumption. The heart of the system is the compressor which relies on your engine’s drive belt to run. Running the belt increases the load on the engine, leading to an increase in fuel consumption. Some research suggests it can increase it by about 20% but most of the time you won’t notice it.
How To Make AC Colder In Car
You can’t replace the AC system in your car. Chances are it’s been designed to work with your specific car, and there are no aftermarket solutions. The best you can do is ensure you have a clean cabin filter and replace faulty components. One more tip: turn off the recirculation mode when you first turn on the car, this helps to get rid of hot air inside the cabin and maximizes your AC’s cooling efficiency.
Why Doesn’t My AC Work In My Car: In Conclusion…
In conclusion, the AC in your car fails in several different ways. The most common one is when the air coming out of the vents isn’t cold. But the heater and the fan can also fail.
Due to this, the solutions and repair costs also vary. Your car’s make and model will also affect the cost, as certain components may be more difficult to access.
Hopefully, this has been a helpful article for you, and now you know what to fix in your car. And if a friend asks you “why doesn’t my AC work in my car?” you can also help them now. Good luck!
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