How To Check the Freon in a Home Air Conditioner?

Knowing how to check the Freon in an air conditioner is an important skill for any homeowner.  Fortunately, this is relatively simple if you know what steps to follow.

To check the freon in a home air conditioner, start by locating the freon line. Next, use a Freon pressure gauge to check the pressure in the line. If the pressure is low, hire a professional to add more Freon to the unit.

Let’s take a closer look at the exact steps involved in checking the Freon levels in an AC.

1. Locate the Freon

This is one of the most difficult steps when checking the Freon level in an AC. Freon is often located in hard-to-reach places, making it difficult to check the level without the proper tools.

The Freon is located in the outside unit of your air conditioner. The outside unit is the larger of the two units and is usually on the ground. The inside unit is the smaller of the two units and is usually on the wall. 

You will need a screwdriver, a pair of pliers, and a flashlight to check the Freon level. Once you have located the Freon, you need to unscrew the cap on the tank. Be careful not to go hard on the cap, as this can damage the Freon tank.

Read: How Long Does Freon Last In Home AC?

2. Use Pressure Guage To Check the Freon

You will need a pressure gauge to check the Freon levels in your home air conditioner. You can purchase one at most hardware stores or online. If you prefer the convenience of shopping online, I’ve got a great suggestion: The universal Honhill Air Conditioner Gauge( available on It’s easy to use, with joints fitted with shut-off valves to prevent Freon loss.

Universal Honhill Air Conditioner Gauge
Buy on Amazon
We earn a commission if you make a purchase, at no additional cost to you.
02/18/2024 02:11 am GMT

Okay, you have your pressure gauge on standby. What’s next? 

Attach it to the Freon tank and turn it on. The pressure gauge will indicate your AC’s current Freon pressure level. 

If you get an extremely high-pressure reading, you might have a Freon leak. This is something you shouldn’t ignore. Not only can a Freon leak damage the air conditioner, but it can cause health issues such as:

Have a Question? Ask HVAC Technician

Click here to use the chatbox to speak with one of our technicians.
No in-home service calls. No appointments.

  • Headaches.
  • Eye irritation.
  • Vomiting.
  • Nausea.
  • Respiratory complications like coughing and breathing difficulty.
  • Skin irritation.

On the other hand, an extremely low reading could mean that the Freon needs to be refilled. This, too, needs immediate attention. If your AC doesn’t have enough freon, its cooling efficiency will be significantly compromised.

Read: Freon In AC – Everything You Need To Know About

Other Methods of Checking for a Leak in Your AC Unit

Aside from using a pressure gauge, there are several alternative techniques to check for a leak in your AC unit. These include:

A Sound Test

If your air conditioner makes a hissing or bubbling sound, there is likely a leak. Freon often leaks in the internal valve or the AC’s refrigerant lines.

To pinpoint the exact location of the leak, listen to where the sound is coming from. If it’s from the lines, that’s where the leak is. The same goes for the internal valve.

Read: Does Freon Gas Smell?

The Soap test

This is one of the oldest and most effective ways of testing for a leak in your air conditioner. Simply apply a soap and water solution to your Freon tank’s potential leak points. If there is a leak, you will see bubbles forming.

Here’s a handy video with easy-to-follow instructions on how to perform the soap test:

Using Electronic Detectors

Finally, you can also test for leaks electronically. There are a few different devices you can use to do this, but most people use a freon leak detector because it comes with powerful sensors that detect very small leakages.

If you don’t have a Freon leak detector and would like to purchase one, I’d recommend getting the Elitech WJL-6000. This battery-powered device is one of the most cost-effective options out there. It also comes with adjustable sensitivity, allowing you to detect even the smallest leaks.

Read: R22 Refrigerant – Everything You Need To Know About

3. Have a Professional Recharge the Freon if Necessary

While some people may be tempted to recharge their home air conditioning unit themselves, it’s important to leave this task to the professionals. Hiring a professional ensures that:

There’s also a safety reason to have a professional handle the recharge. Freon is a dangerous chemical that can cause serious health problems if not handled properly. For instance, it can cause skin burns, vomiting, nausea, and dizziness. It can also irritate your eyes, ears, and your respiratory tract. 

How To Know if Your Central Air Conditioner Needs Freon?

Before you hire a professional to perform a freon recharge, you need to be sure that your AC actually needs it. This way, you don’t waste time and money on something that doesn’t need fixing. 

There are a few clues that the air conditioner needs to be recharged. 

Your Air Conditioner Is Blowing Warm Air

If your AC blows warm air, it could signal that your system is low on Freon. To help you understand why this is the case, let’s quickly review the role of Freon in the cooling system.

ACs cool by blowing warm air from indoors over the AC coils, where the Freon is housed. As the warm air runs over these coils, the Freon inside them absorbs the heat from it, cooling it down. The cooler air is then re-circulated through your home, cooling your indoors. 

If the freon level falls below a certain level, the warm air runs over the coils without losing heat. As a result, your AC starts blowing warm air. 

More often than not, an AC that’s low on freon will start out fine and then start circulating warm air after running for a while. This is the telltale sign that the warm air from an AC is due to low freon levels. 

Read: How Cold Is The Air That Comes Out Of The Air Conditioning Unit?

Electric Bills Are Higher Than Before

If your electric bills have been gradually increasing even though your usage hasn’t changed, it could be a sign that your air conditioner is low on Freon. 

An AC’s cooling efficiency is significantly compromised when it’s low on Freon. When this happens, the AC runs on more power than usual, and that’s reflected on your electricity bill.

Hissing Sound Coming Out of the Unit

An air conditioner can make all kinds of strange noises, but hissing shouldn’t be one of them. The problem is the hissing doesn’t necessarily mean that your unit is low on Freon. It can be caused by different AC issues, including a Freon leak.

As such, you should only take hissing as a sign of low Freon if it’s accompanied by the other signs I’ve outlined above.

For more insight on how to fix common AC problems, check out my troubleshooting guide. It covers common problems with newer AC models and their fixes.  


As you can see, checking the Freon level is a relatively simple process. If you’re up for it, get the necessary tools and follow the above steps.

The one step I don’t recommend tackling on your own is the Freon recharge. Leave that to the professionals because mishandling Freon can have serious health consequences, not to mention that you might get the whole recharge process wrong and end up damaging your AC.