Why is My Car Air Conditioning Blowing Hot Air?

There’s nothing better than cranking up the AC in your car on a hot day. Still, what happens when your car’s air conditioning starts breaking down and will only blow hot air? What could potentially cause a problem like that, and is there anything you can do about it? 

If a car’s air conditioning will only blow hot air, it likely either has a problem with refrigerant or its electrical system is malfunctioning. It is best to use a leak detector and make sure there is no refrigerant leaking anywhere. If there is no leak, you need to troubleshoot the components involved in the AC’s function. 

If you’d like to get your car’s air conditioning back on track, you’ve come to the right place. In the sections below, we’ll help you navigate the troubleshooting process by zoning in on what exactly could cause this problem.

How Your Vehicle’s Air Conditioning System Works 

Before we explore the specific problems you may be having in greater detail, it is important to understand how a vehicle’s air conditioning works in the first place. 

The air conditioning system doesn’t create cold air. Instead, it takes all of the heat and moisture out of the air and then recirculates the cooled air. For this process to work, you need a refrigerant to remove the heat, a compressor to circulate the cool air, and a condenser to keep the refrigerant itself cool. 

At any stage in this process, things can go wrong. That’s why when you’re troubleshooting, you want to start with the most simple component first. In this case, that would be the refrigerant. 

Common Causes of a Car’s AC Blowing Hot Air

If your car is exclusively blowing hot air, you likely have a refrigerant problem. Refrigerant is sometimes called Freon, after the best-known brand name. It is a liquid that circulates through your car’s air conditioning system to capture heat and keep things cool. 

Your problem could be one of several issues, including:

  • The refrigerant isn’t being kept cool itself
  • The refrigerant is failing to circulate properly
  • There is a leak 

Is Your Refrigerant Leaking?

Refrigerant leaks are more challenging to spot than others because as soon as the refrigerant hits the air it evaporates. So how do you find a refrigerant leak, and what do you do about it? 

Conducting a Visual Inspection for Leaks

You can start with a visual inspection. As we said above, refrigerant leaks don’t generally leave a whole lot behind for you to see. However, using UV dye and UV light, you can hack your way around that problem.

Some cars already use UV dye in their system to help you find these leaks; however if yours doesn’t, you’ll want to add some to it. Then you want to remove caps and check around service ports for any sign of the dye. You can use UV light to see this more easily.

If you find where the dye is coming from, you will have found the leak and can act accordingly. Don’t worry; if this process sounds too complicated or complex, we have another way you can find a leak that just involves pointing a device in the right direction.

Using a Leak Detector to Find Leaks 

Perhaps the simplest way to find a leak, is to use a device called a leak detector. Leak detectors (also known as sniffers) detect refrigerant in the air. They will alert you when they sense a refrigerant leak. 

Please note that refrigerant is heavier than the air, so you should check the low areas where it could be leaking to save some time. 

Below are the steps you should take:

  • Make sure your refrigerant is full and that the car is off in an area with minimal wind before you start testing to find out where the leak is coming from.
  • Turn on the detector and point its wand around the engine where you suspect a leak. We recommend that you start with your O ring seals and then survey your whole condenser and all its hoses methodically. On your first go-through, you want to use the lowest test setting. If it passes that, try one more time in a higher setting just to be sure.
  • If the detector begins to beep quickly or you see flashing lights, congratulations, you have found the source of your leak! Please remember to try and keep the sensor tip at the end of the wand away from dirt through this process so you can extend its life and have it if this problem ever happens again. 

If you don’t feel comfortable looking for the leak yourself, bring your car to a trusted mechanic. If you are in the Little Rock area, give us a call at 501-214-1091!

Is Your Problem a Broken Compressor?

Your compressor is what ensures that your refrigerant circulates through the car and makes it to your condenser to cool things off. If it ends up broken, you won’t have any circulation, and thus only hot air. 

You should suspect the compressor if your car has been sitting stagnant for some time without using the AC. This is why mechanics recommend that you run your A/C for a little bit when you’re defrosting your car in the wintertime. 

It is usually less expensive to replace the compressor entirely. Having an old one fixed would likely end up costing more money and time. 

Do You Have a Problem With Your Condenser

You’ll find your condenser at the front end of your car near the radiator. The condenser essentially keeps your refrigerant cool when it absorbs heat. If it isn’t working, eventually, your car’s AC will blow nothing but hot air. 

First, visually inspect the condenser for any potential corrosion that has taken place. Many mechanics suggest that you visually check it for corrosion periodically, even when it’s working fine, so you can identify and stop problems before they start. If you’ve been in an accident recently, it’s entirely possible that you simply broke it, so you’ll want to look for signs of that as well.  

If there is severe enough corrosion you will need to get it replaced. However, if there has just been a buildup of gunk gumming up the works, you can potentially have it cleaned externally or through an internal flush. 

Electrical Problems Causing Your Car’s AC to Blow Hot Air

If the components involved in circulating and cooling your refrigerant are not damaged, but you still don’t have any cool air, your problem is likely electrical.   

To solve this, you’ll want to complete a visual inspection, wherein you check your fuses and the wiring for anything that seems out of place or anything that isn’t working. This can be an exhaustive process, so you may want to bring it into a shop and make sure you haven’t missed anything yourself if you don’t have much experience working with car electrical systems. 

So Really, Why Is My Car Air Conditioning Blowing Hot Air?

If your car’s AC only blows hot air, you are likely having a problem with the components related to your refrigerant, or you are having electrical issues. For the refrigerant, you’ll want to make sure there are no leaks and that both your condenser and your compressor are functioning properly. You can do this through visual inspections and by using a leak detector if that happens to be the problem.

If you think the problem is electrical, you’ll want to check all of your fuses and make sure everything else electronic is functioning correctly. You’ll also want to check any wiring to be sure everything is connecting that should. Once you’ve located the problem, you can take care of it and get back to driving around comfortably. 

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