The summertime can be grueling if the air conditioning in your car is not working properly. Imagine hopping into your vehicle on a hot day and flipping on the air conditioner. The air coming from your vents feels more like heat instead of the AC. You end up flipping the air back off and just rolling down the windows. Now you’re stuck wondering what is wrong with your AC system while you sweat on your way to your destination. We are here to tell you five common reasons why your car air conditioner is blowing hot air and tell you how those problems can be fixed.
How Your Car’s Air Conditioning System Works
Your car’s air conditioning system works much the same way that the air conditioner in your home works. However, all the parts are generally smaller and are situated under the hood of your car. There are many complex parts that all work together to remove heat from the air, thus causing your air conditioner to blow cold air. The process is very complex as well, but here is how things work at a high level.
First, your air conditioning system requires refrigerant. This refrigerant is converted back and forth between high pressure and low pressure and gaseous and liquid states. The compressor is the part that compresses the refrigerant from low pressure into a high-pressure state. The condenser and evaporator are parts that act like small radiators in the system. They remove heat from the refrigerant as it passes through these parts. There are also cooling fans that blow on the condenser to assist in the removal of heat. The receiver, or dryer, removes moisture from the system to help prevent your system from freezing. Finally, the expansion valve controls the amount of refrigerant that flows through the system. It acts like the nozzle on a hose and can control how much refrigerant flows through.
This is an extremely high-level overview of how your AC system works. A problem with any of the parts in your system can cause the entire process to fail. So, what is the problem when you feel your AC blowing warm air? Let’s dive in and take a look at the most common causes.
5 Reasons Your Car AC Might Be Blowing Hot Air
Your car AC can malfunction for various reasons, and here are some of the most common ones.
— Electrical System Malfunction
Though it sounds like your air conditioning is a very mechanical process, many of the parts in the system require electrical power to operate. Your compressor and cooling fans both use power from your vehicle’s electrical system to run. Therefore, electrical issues can cause your car air conditioner to stop blowing cool air. This could be something as simple as a blown fuse, a bad relay, a broken wire, or even low output from your alternator. It can be difficult to diagnose electrical problems, so you might need a good mechanic to help you track down this problem.
— Low Refrigerant Level
A low refrigerant level is probably the most common cause of a blast of hot air coming from your car A/C vents. Since your air conditioning system is a closed system, a refrigerant leak is really the only way that the level could become low. Leaking refrigerant might be due to a small puncture in one of the cooling lines, a bad seal in the compressor or road debris hitting the condenser. Since the condenser is located at the front of your car, debris from the road can hit it and cause damage. Small leaks can often be repaired with a coolant sealant, but bigger leaks might require more work.
— Bad Compressor
A bad compressor will quickly ruin your vehicle’s air on a hot summer day. If your compressor is not adequately compressing the refrigerant in the vehicle’s A/C system, then you will not feel any cold air from your vents. Your AC compressor could be locked up, or it might have a blockage internally. Repairing or replacing a bad compressor generally requires specialized tools and expert knowledge, so this job is best left for an experienced mechanic.
— Malfunctioning Condenser
A broken condenser will also quickly ruin your car’s AC system. If you are wondering, “Why is my car AC not blowing cold air,” it might just be because of a bad condenser. If there is anything blocking airflow through your car’s front grille, then this causes problems as well. This will prevent air from flowing through the condenser and removing heat appropriately. As part of your regular car care, make sure to inspect your grille in the front of the car for debris or other items that could prevent proper airflow.
— Broken Cooling Fans
Broken cooling fans can also cause similar problems to a bad condenser. If the fans are not blowing air across the condenser, then heat will not be removed from the system. This will become even more evident during long periods of idling or driving very slowly. As your car drives, the fans are not as important because air flows across the condenser naturally due to the speed of your vehicle. However, as your car sits and idles, there is no airflow without the fans.
Recharging Your Car’s AC System
When your AC refrigerant levels get low, you can recharge your system to get it working properly again. If your system only has a very small leak, a simple recharge might allow your AC to work fine for another year or two. Many people wonder how to put freon in a car. You have likely seen those “AC Recharge In A Can” systems at your local auto parts store. While these can be effective, they can also damage your AC. Overcharging your system can have detrimental effects, and it can also be dangerous. It could cause a blown line or other issues while you are attempting to recharge it.
You should always take your car to a certified mechanic to recharge your AC system. Your mechanic will know the proper type of refrigerant to use in your vehicle, and they will also know the proper pressure for your system. They will have the correct tools to use to recharge the system, and they can ensure that no additional damage is done because of putting too much refrigerant into the system.
Car Air Conditioning Repair Cost
Now that you know some of the potential issues, how do you fix the AC in your car, and how much is the auto repair going to cost you when you head down to your local automotive center? It depends on the specific problem. You are likely to find that your local repair shop will often run specials on AC recharging. You might be able to get your AC charged for as little as $79. If low refrigerant is the problem, then this solution might keep your AC working for another year or two.
However, if you have bigger problems like a bad compressor or bad cooling fans, then you are probably looking at a bill of $500 to $800. Some vehicles will be even more expensive. If you have a high-end car like a BMW or Mercedes, then your bill for this repair could be well over $1,000. As always, independent repair shops are almost always cheaper than your dealership, and many of them perform high-quality work.
The Bottom Line
Driving around in the summer with a car AC that blows hot air can be almost unbearable. In some parts of the country, even rolling your windows down doesn’t help enough. Plus, rolling your windows down while driving lets all the great smell from your car’s air freshener escape right out! You need to figure out what’s causing the problem and get it fixed quickly. Hopefully, you only need a simple AC recharge to get things working again. However, if you need to replace the compressor or other critical parts, then you will likely have an expensive repair bill.
Frequently Asked Questions
What is the best way to fix my car’s AC?
The best way to fix the AC is to have it diagnosed and repaired by a qualified mechanic. They can test the system and easily determine whether the refrigerant level is low. If it is, then they can recharge the system and get things working again without incurring a huge expense. If there are bigger problems, the repair becomes even more complicated, and the help of a mechanic is crucial.
Is it normal for my car’s AC to blow hot air?
Your AC may blow warm air for just a few seconds when you first turn it on. However, it should begin to cool off quickly. Within 30 seconds to a minute, even in the middle of summer, your AC should be blowing cold air from the vents. If it is not, then you have a problem. Let a mechanic take a look so that you can get your air working properly again.
Why is my AC running but not cooling in my car?
Perhaps you are wondering, “Why is my AC blowing hot air?” If your AC is running but not cooling, then it is likely that your refrigerant is low. You can also open the hood and determine whether the compressor is running. If the compressor is not running, then there are a couple of possibilities. You could have an electrical problem that is preventing it from turning on. It could have gone bad and locked up. Or, the refrigerant may be so low that the compressor shuts off to avoid damage. If the compressor is running, then you may only have a slightly low refrigerant level, or you could have other issues like a bad condenser or cooling fans.