How to Add Freon to an AC Unit: A Step-by-Step Guide (2023)

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Air conditioners that are not cooling properly or have icy-looking coils may have an underlying issue: leaking refrigerant. Freon is a common refrigerant that, while no longer in production, is used inside many AC units as a coolant to create cool air. While most air conditioners will never need Freon added, there are some occasions when it is necessary.

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Use this guide to learn how to add Freon to your AC unit and why you may want to consider hiring a professional to take on the task.

Why Does Freon in an AC Unit Need Replacing?

Freon is the coolant that allows your air conditioner to cool down the air in your home. Also called R-22 refrigerant, Freon switches between liquid and gas forms. The freon circulates inside an AC unit in a closed loop, and because of that, you ideally shouldn’t need to replace it. However, you must replace the lost Freon if the coolant piping has a leak or another issue.

Unfortunately, due to Freon’s negative impact on the environment and ozone, it is no longer in production. An HVAC professional will likely still be able to find Freon for your older AC unit, but new units use other types of refrigerants, like the more favorable R-410A refrigerant.

How Much Does It Cost to Add Freon?

Adding R-22 Freon refrigerant to your AC will cost anywhere from $100 to $350. It can cost as much as $600 for larger AC units requiring more refrigerant. Freon costs $90 to $150 per pound when purchasing through a professional, so besides labor costs, a big portion of the price depends on how much refrigerant has leaked out and needs replacing.

How Often Does Freon Need to Be Added to an AC?

Freon only needs to be added to an AC if there is a leak in the system. Since Freon travels in a closed loop inside the AC unit, you will never run out of it. If your air conditioner is not cooling as expected, your utility bill is higher than normal, or there is another similar issue, recharging your AC by adding new refrigerant could solve the problem. An AC actively leaking refrigerant may have ice on the evaporator coils, make a hissing sound, or give off an exhaust smell.

Should You DIY Adding Freon to an AC Unit?

Adding Freon to an AC unit is not a typical DIY project. It requires working with a dangerous chemical, a pressurized tank, and intricate equipment. Any part of the process going wrong can permanently damage your AC unit or cause injury to yourself. Seriously consider contacting a local HVAC professional for this type of service.

How to Add Freon to an Air Conditioner

How to Add Freon to an AC Unit: A Step-by-Step Guide (1)

Photo: Myrku / iStock / Getty Images Plus / Getty Images

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Once you have determined that your AC needs more refrigerant, you can follow this step-by-step process. Carefully read through each step before getting started to make sure it is a project you’re up to.

1. Determine Whether You Have a Refrigerant Problem

You only need to add Freon to your AC if it leaks out of the system. Two common signs that you may have a refrigerant leak include your AC blowing out warm air when it is set to a cool temperature or ice building up on the coils. Adding Freon to your AC unit could help fix these two issues.

2. Choose the Correct Refrigerant

Make sure your specific air conditioning model actually uses Freon. Many types of refrigerants are available, and Freon or R-22 is not used in newer AC models. Read the manufacturer’s product information or complete the necessary online research to determine if Freon is the right refrigerant for your AC.

3. Put On Safety Gear

Freon is a dangerous chemical that can cause irritation or burns if you come into contact with it. It is important to protect your skin and eyes while working with refrigerant. During this project, you should wear safety goggles, gloves, a respirator, and protective clothing. If you are not comfortable working with a chemical with these potential risks, there is still time to hire an HVAC tech who is experienced and knows the risks.

4. Consider the Outside Temperature

Only add Freon to your AC unit if the outside temperature is above 55 degrees Fahrenheit. Once you put Freon in your system, it will move toward the coldest area. In cooler temperatures, this can cause the refrigerant to escape to the outside air rather than remaining inside your AC.

5. Turn Off the Power to the AC

Start the process of adding Freon to your air conditioner by turning off the power. Go to your breaker box and turn off the breaker that powers your AC unit.

6. Attach Refrigerant Gauges to the AC

When you purchase Freon (if you can do so, as typically only licensed HVAC technicians can get their hands on it), it comes in a compressed cylinder with a pressure gauge and hose setup. First, attach the blue hose to the low-pressure port on your AC unit’s suction line. Similarly, attach the red hose to the high-pressure port on the thin copper line.

7. Turn the AC Back On

Turn the breaker to your AC unit back on and let it run for about 15 minutes. This stabilizes the unit and ensures the pressure gauges get an accurate reading.

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8. Hook Up the Hose and Add the Refrigerant

Grab the yellow hose and attach one end to the valve on the Freon cylinder. Attach the other end to the valve in the middle of the pressure gauges. You can now twist the valve near the bottom of the Freon cylinder to open it up, and you’ll likely need to twist it several times.

Next, open up the valve near the blue low-pressure gauge for a few seconds, then immediately close it. Repeat this step, opening and closing, until you reach your desired temperature. The temperature is displayed on the outdoor unit rating plate. You will only add refrigerant through the low-pressure side and in small increments.

9. Disconnect the Hose and Gauges

With enough refrigerant added to reach your desired temperature, you can now turn off the blue low-temperature valve and close the knob at the bottom of the Freon cylinder. Disconnect all of the hoses and re-install the caps.

10. Fix the Underlying AC Issue

Adding Freon to your AC is just a temporary fix. You will need to figure out why the refrigerant was leaking and make the necessary repair to prevent future leaks. Only a licensed HVAC professional should complete this work, so reach out to one in your area.

How to Prevent a Refrigerant Leak in Your AC

Regular maintenance of your AC system is crucial to preventing a refrigerant leak. Having your AC serviced at least once per year by a professional HVAC technician is ideal. During this tune-up, the pro will look out for signs that a leak could happen and make any necessary repairs to prevent it. The technician will also top off your refrigerant if it is below the necessary level.

Frequently Asked Questions

While it is possible to add Freon to your AC unit yourself, it is not recommended. In fact, the U.S. Environmental Protection Agency (EPA) advises against it. Freon is a dangerous gas that can cause irreversible damage to your AC or yourself if not installed correctly. It is worthwhile to hire a professional to add Freon to your AC.

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