Car A/C blowing hot air – causes and fixes

The A/C system is arguably one of the main features of your car’s interior, especially if you want to feel the cold breeze on your skin during extremely hot days. However, if you are having a problem with the car A/C blowing hot air, it can be a devastating thing during the summer.

Fortunately, our team realized the gravity of the situation, so this guide should help you out if hot air passes through your A/C vents. We’ll dive into the possible causes and what you can potentially do to fix the annoying issue of hot air with the climate control on.

Why is my car’s A/C blowing hot air?

Your car’s A/C could be blowing hot air due to a faulty A/C compressor, an issue in the car’s electrical system, or a lack of refrigerant. However, it can also be due to other factors, so here’s a complete list of possible causes:

• Electrical faults
• Condenser issues
• Not enough refrigerant or a leak
• Broken compressor
• Faulty cooling fans

The good news is that you can find out the cause of the problem by getting the A/C system of your car examined. It’s rarely an issue that neither you nor the mechanic can find a solution for, but it still presents an annoying task.

It’s quite common that drivers simply forget to service the A/C unit on time, especially in terms of charging the refrigerant. On the other hand, it might be tough to find the exact leak, in which case things get a bit more complicated. We’ll go over all the possible causes to help you out in case you face this issue.

Troubles with the electrical system

This is a specific situation since the issues in your car’s electrical system aren’t directly connected with the A/C system. Well, at least the battery and other electrical components aren’t part of the A/C system, while it still needs electricity to work properly.

For instance, if you get a battery discharge warning displayed, you might have a malfunctioning A/C compressor. It’s a clear indicator of a faulty compressor, which is the essential component of your A/C system. It affects the temperature of the air by pressuring the refrigerant, so you get a cold airwave during the hot summer days.

Other than the issues that might cause the lack of compressed air, your electrical system might simply have a blown fuse or a burnt wire. So, even if all the components of your A/C system are operational, the electrical system won’t let it work properly. In this case, replacing the problematic wire or a fuse can get your climate control function back on track.

The condenser isn’t working properly

Another common issue that you might face is a malfunctioning condenser which prevents the distribution of cold air from your A/C system. Even if you don’t have a low refrigerant or a leak in the system, a faulty condenser could prevent it from keeping its cool state.

If you have enough refrigerant or freon, the condenser keeps it cooled by keeping it in a liquid state. The freon keeps changing from gas to liquid during the A/C cycle as it cools the air that exits through A/C vents. However, if the condenser is faulty or broken, the freon won’t be able to fulfill its purpose and cool the air.

That’s why you might experience hot air blowing through the A/C unit even though the freon is filled-up. In case you go over a large bump on the road or hit a low obstacle and in range of the condenser on the front of your car, you might damage it. In this case, you might notice foggy smoke coming through the grate.

Low or leaking refrigerant

You might not know this, but it sometimes takes re-filling the freon in your A/C unit to ensure the proper air cooling process. Regularly, it only takes replacing the freon once in a few years, but if you have a refrigerant leak, you’ll have to do it more frequently.

Of course, the solution is to repair the leak, but it’s not always that simple. Namely, freon evaporates in case of a leak, so it can be hard to trace it. Mechanics usually use dye to trace the leak by placing it in the system and closely observing where it leaks.

Once you repair the leak and fill up the freon, you’ll instantly be able to use your A/C with cool air reaching the cabin.

Stuck cooling fans

Cooling fans are yet another important component of your car’s A/C system, and they can sometimes be broken or stuck. Dirt and debris could get into the system and create a barrier that the fans can’t burst through.

Since these fans work together with the compressor to cool down the air, you could be getting hot air because of this. If the fans are causing the air from your A/C unit to be hot, you can replace them and get them rolling again to cool the air.

Make sure to check the filter

Another possible reason why you only get hot air blown from the A/C unit could be the clogged cabin air filter. Your air conditioning filter can get all dirty and clogged, therefore preventing proper airflow. A clogged or dirty filter is your next stop when it comes to things worth checking in case of hot air blowing from the vents.

Not only does it affect your receiving cool air during the summer, but it also ensures you have plenty of clean and breathable air in the cabin. In case your cabin air filter gets clogged, you’ll notice the specific bad smell in the cabin, and that’s an alert to inspect it.

How do I fix my car AC from blowing hot air?

You can fix your A/C unit from blowing hot air by getting the entire system thoroughly inspected. Sadly, even though you might be able to check the air filter yourself by the guidelines from the user’s manual, you’ll probably have to visit a mechanic.

It’s the only way you can be sure that the matter has been taken care of. A mechanic will check your compressor, condenser, and refrigerant to make sure everything works properly. If that’s not the cause of the issue, they will take a look at the electrical installations of the system.

So, you can try to check the air filter on your own, but it’s best not to tamper with the A/C components without help.

Our take

Ultimately, in the case of a car A/C blowing hot air, there’s not much you can do to fix it yourself. However, you can rely on potential issues discussed in this guide to diagnose the issue and possibly make it even easier for the mechanic.

Sometimes it just takes refilling the freon, since it rarely lasts for more than 5 years even without a leak. The A/C unit is a complex system in your vehicle, but you’ll find a solution quickly by paying attention to what happens when you turn the A/C on based on the pointers in our guide.