Car AC Blowing Hot Air – Causes, What to do & Repair Costs

During the hot summer months, the last thing you want is an air conditioning unit that blows hot air on you. But while it’s uncomfortable and unwanted, it’s also a bit more common than you might think.

But while a car AC blowing hot air is a common problem, troubleshooting it is a little more unknown, as is how to fix it. That’s why we wanted to come up with this guide for you to highlight a few reasons it might be happening.

Not only that, but we’ll give you some tips for troubleshooting and fixing the problem, and we’ll even give you a general idea of how much you can expect to fix each potential issue.

7 Reasons Your Car AC Is Blowing Hot Air

When you have a car AC blowing hot air, you first need to figure out why it’s happening. There are a few different reasons your car AC might blow hot air, and we’re going to highlight seven of the most common reasons your car AC is blowing hot air.

Refrigerant Leak/Low Refrigerant

By far, the most common problem when your car AC is blowing hot air is a refrigerant leak or low refrigerant. Even if there’s nothing wrong with the refrigerant in your car, it only lasts about five years before you need to replenish it.

It’s one of the first things you should check, and if that is the problem, there’s a good chance you can fix it yourself without spending a ton.

Broken Condenser

Did you know when the refrigerant leaves the AC compressor on your vehicle, it’s actually hot? It’s the condenser’s job to cool it back down and turn it into a liquid, and it does a pretty good job.

But if the AC is coming through the vents and it’s hot, then there’s a chance that the condenser isn’t doing its job. A typical air condenser will last about ten years, so if it’s getting around that time for your vehicle, the condenser might be the problem.

Bad Compressor

If the refrigerant isn’t the problem, a bad compressor is often the issue people jump straight to. But the truth is that most AC compressors last between ten and fifteen years, so they’re not going bad as often as you’d think.

But if your air conditioning isn’t blowing hot air and there’s plenty of refrigerant in the system, the AC compressor might be the problem.

Malfunctioning Electrical System

Just about everything in your vehicle uses electronics to run, and the air conditioning system isn’t any different. Whether it’s turning the system on, changing the temperature, or a whole host of other functions, it all comes down to the electrical system.

But if there’s a short, a blown fuse, a broken line, or simply a disconnected switch, nothing will know what to do. Plenty of amateur mechanics have thrown tons of parts and money at their AC problems only to find out that a ten-cent fuse could’ve fixed their problem from the start.

Broken Blend Door

Sometimes people wrap this issue up with electrical problems, and while it certainly can be, it’s not always a problem with the electrical system. The blend door itself can simply fail, or there can be something obstructing the blend door from opening or closing.

Since the blend doors open and close to redirect airflow, a damaged blend door can affect the temperature of the air coming from the vents.

Another problem that’s unique to blend doors is that something can get stuck in them and prevent them from opening or closing when they should. This usually happens when something accidentally falls into one of the vents and then works its way to a blend door before getting stuck.

It’s On the Wrong Setting

female hand with pink nails pointing on car AC button

Sometimes the problem comes down to user error. While it’s not fun to think about, do yourself a favor and make sure you turn down the temperature setting in your vehicle’s AC system.

Sometimes we just get so busy with life and get so freaked out when something doesn’t go our way that we forget to look at the simple stuff. So, take a step back and look at the temperature knob in your vehicle.

And if that is the problem, don’t beat yourself up too much, it happens to the best of us.

The AC Hasn’t Warmed Up Yet

As soon as you turn on the car you want the cold air to start blowing on you. That’s not how it works. You’ll need to give the compressor a little time to warm up. Give it three to five minutes and see if you can’t feel a difference in the temperature.

If you can, the air conditioning is working, at least to some degree. Finally, keep in mind that it might not feel like the AC is cooling down your vehicle as much as you would like if it’s extremely hot outside. You can upgrade some components to try and get a more effective AC system, but you still might not get the ice-cold results you want.

Overcharged AC

On rare occasions, you could be dealing with an overcharged AC. However, this is likely only the case if you recently charged the AC system yourself or had someone else do it for you, and the job was done improperly.

But if you did, there’s a good chance you have the answer to why your car AC is blowing hot air.

Related: AC Overcharged – Symptoms, Causes, and Fixes

Troubleshooting a Car AC Blowing Hot Air

With so many potential causes of a car AC blowing hot air, it can be a little overwhelming to figure out how to narrow it down to one specific condition. That’s why we came up with this guide to point you in the right direction and get you back on the right track.

When starting the troubleshooting process, keep it simple and rule out the easy things first. Start by ensuring that the knob is on cold and that you’ve given the vehicle plenty of time to warm up.

Next, do yourself a favor and rule out the fuse. It’s not the most likely problem, but it’s one of the easiest to rule out, and you don’t have to spend a dime on anything to check it.

The next easiest thing to check and rule out is if there’s refrigerant in the system. Unless you already have an AC hose, we recommend getting a kit like this one that includes both the hose to check the level and the refrigerant to fill it back up.

Even if you don’t need the refrigerant this time, it’s likely only a matter of time until you need to top the system off.

Next, see if the AC compressor will turn on. If it does, the problem is likely with the condenser. Either way, we recommend taking your vehicle to a certified repair shop.

This is because you can’t legally evacuate the refrigerant into the atmosphere. So, if you have to remove any of the components, it’s best to do the right thing and take it to an authorized repair shop that can collect the refrigerant instead of sending the harmful chemicals into the atmosphere.

How Much to Fix a Car AC Blowing Hot Air

While the exact cost to repair a car AC blowing hot air will come down to your vehicle’s exact problem, we’ll highlight how much you can expect to spend to repair some of the most common reasons for this condition.

If the problem is the refrigerant and it’s not a leak, a professional shop will charge you between $100 and $300 for the recharge. But if you’re willing to do the work yourself, it typically only costs between $50 and $75 for everything you need.

If the condenser is the problem in your car, the repair cost can vary quite a bit – anywhere from $300 to $1,000 is typical for replacement, while an AC compressor can cost you anywhere between $1,000 and $1,500.

If you’re taking your vehicle to a repair shop and they diagnose a faulty component in the electrical system or a broken blend door, you can expect to spend between $200 and $500 on repairs.

Keep in mind that even if the mechanic catches something simple like a fuse, they’ll still charge you between $50 and $100 for a troubleshooting fee.

It still takes time for a mechanic to figure out what’s going on with your vehicle and replace the component, and they’ll charge you for their time even if the fix is easy.

Most shops have a flat rate troubleshooting fee they’ll charge you no matter what they figure out and diagnose the vehicle with.

Final Thoughts

If you have a car AC blowing hot air you don’t have to keep dealing with it. Hopefully, after reading through some of the potential causes and with some of the troubleshooting tips we gave you, you can diagnose your faulty AC system and get it back to blowing cold air.

And if you can’t, you can always take your vehicle to a certified repair shop, and they’ll troubleshoot and repair the issue for you. Of course, if you can’t figure it out, you can always just roll down the windows and hope for the best.

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Rickard Cefalk

Rickard is the owner of and a dedicated and avid do-it-yourselfer who has always enjoyed working on his own vehicles since childhood. He now devotes his time to sharing his expert knowledge of car maintenance and other car-related information through his website.

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