How to Add Freon to an Air Conditioner (And When to Hire a Pro)

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How to safely fill your AC’s refrigerant
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If your AC unit is leaking or isn’t producing cool air, it may need more Freon, or refrigerant. Adding Freon is extremely dangerous, so the process should be done by a professional HVAC technician whenever possible. However, it is technically possible to do it yourself if you have the knowledge and tools required. In this article, we’ll explain how to handle refrigerant safely , add it to your AC unit , and determine whether your unit needs more refrigerant with tips from air conditioning technician Victor Belavus. Plus, learn when Freon needs to be replaced, how much it costs, and how to prevent refrigerant leaks.

How to Add Refrigerant to an AC Unit

  1. Make sure you have the right type of refrigerant, and put on safety goggles and gloves.
  2. Turn off your AC unit at the breaker, and hook up the refrigerant gauges.
  3. Turn the unit back on, wait about 15 minutes, then open the canister of refrigerant.
  4. Open the blue valve for a few seconds at a time to slowly allow refrigerant into the unit.
  5. Turn off the valve and disconnect the gauges when you reach the target subcooling temperature.
  6. Perform an electronic leak test to ensure your unit is running safely.
Section 1 of 7:

How to Use Refrigerant Safely

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  1. It is highly recommended that a qualified professional refill and recharge your AC unit. The procedure itself is dangerous, and if done incorrectly, you can damage your unit. Homeowners are permitted to add some refrigerants in the U.S., but the Environmental Protection Agency (EPA) requires that only licensed technicians can handle R-22, or Freon. Belavus explains, “Unless you have EPA certification, you will need professional help.”
    • Proceed with caution if you decide to do this yourself. Improper handling of refrigerant can cause injury, death, explosions, and property damage.
    • Note: We often use the term Freon to describe any refrigerant, but it technically only refers to R-22 refrigerant. If this is the type of refrigerant your AC requires, you are technically breaking the law if you handle the chemical yourself.
  2. Belavus recommends inspecting your AC for signs of mold or debris “in the spring, before you start using it.” Your AC’s air filter , blower wheel, evaporator coil , and condenser coil need to be cleaned before you “ charge ” your unit with more refrigerant. Adding more refrigerant to a unit with dirty parts can damage the AC.
    • According to Belavus, “Dirty condenser coils are one of the most common issues. Before every cooling season, roughly in spring, inspect your outdoor condenser unit for any signs of debris on the condenser coil fins. If the coil is clogged, turn the power off to the condenser from the disconnect switch and the electrical panel. Remove protective grills from the sides and clean it with a garden hose.”
    • To clean the evaporator coil, Belavus explains, “Remove a few screws from the evaporator compartment and check for debris on the fins and drain pan. Get a bottle of room temperature water and flush the drain by pouring water into the condensate pan to make sure the drain is not clogged.”
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  3. Putting the wrong refrigerant in your unit can cause combustion, injury, and property damage. Check your AC manufacturer’s operating guide to find out which refrigerant your unit needs. If you don’t have the operating guide, check the electrical control box or the unit’s cabinet for the information. The two most common refrigerants are R-22 and R410A. [1]
    • R-22 is mostly used in older units and has been phased out because it is an ozone depleting material. [2]
    • If your AC is leaking R-22, it’s important that you get the problem fixed as soon as possible. Since R-22 has been discontinued, the price for it has skyrocketed and will only continue to get higher.
  4. Wear safety goggles and thick gloves when handling Freon. Never directly inhale any refrigerant; doing so can lead to sudden death. Some refrigerants are particularly hazardous and require respiratory protection—read the packaging for more information. [3]
    • If you get Freon on your skin, rinse the area with water and seek medical treatment immediately.
    • R-717 and R-764 refrigerants are extremely irritating to the eyes and lungs. R-717 is flammable. Handle with caution.
  5. Liquid Freon will automatically seek the coldest area of an enclosed AC unit between the furnace coil and the outside condensing unit. When outdoor temperatures are under 55°F, the coldest area of your system will most likely be the outside unit. The Freon will not behave properly in these conditions. [4]
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Section 2 of 7:

Adding Freon to the AC Unit

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  1. Go to the thermostat that operates your air conditioner. Turn it to the “off” position. Your unit will either have a fused disconnect or a circuit breaker attached to it. If your unit has fuses, disconnect them. If your unit has a circuit breaker, turn the breaker off. [5]
    • Warning: Remember that if your AC requires actual Freon (R-22 refrigerant) it is illegal and extremely dangerous to handle it yourself. It is highly advised to hire a professional HVAC technician instead. Even if you’re adding other types of “Freon” (like R410A) that aren’t illegal to handle, it is best to have a professional do the job.
  2. There are three valve connections attached to your unit’s hardware, with a valve on each side (left and right). Attach the gauge with the blue hose to the low-pressure valve on the left side. Attach the gauge with the red hose to the high-pressure valve on the right side. [6]
    • Leave the center valve open for now; that is where you’ll connect the yellow hose to feed the refrigerant into the system.
  3. After you turn the AC back on, the unit will need to run for several minutes so that it can stabilize itself. You won’t get an accurate reading on the refrigerant gauges until the AC has stabilized. [7]
  4. Attach the yellow hose to the refrigerant canister’s valve, and attach the other end to the middle valve connection on your gauge. There will be a small knob on the bottom of the refrigerant canister. Twist it several times to open the refrigerant. [8]
    • The middle valve is the one between the blue and red valve connections.
  5. Open it for a few seconds, then close it. Open it for a few more seconds, then close it again. Continue doing this. You want to slowly allow small amounts of the refrigerant into the unit at a time until you reach your target subcooling temperature. [9]
  6. The target subcooling temperature is stated on the outdoor unit rating plate. Use the gauge to monitor the temperature so you know when to shut the valve. [10]
    • For example, the rating plate might say something like “10 degree TXV sub-cooling."
  7. Once you reach the target subcooling temperature, turn the valve all the way off. Twist the knob on the refrigerant canister to stop refrigerant from going into the hose. Disconnect all of the hoses and the gauge set from the AC unit. [11]
    • Since the unit is running during this process, there's no need to restart your unit after adding refrigerant.
  8. Buy an electronic leak detector from a home improvement store or online. Each detector is slightly different, but in general, you just need to run the tool along the refrigeration components to scan for a leak. [12]
    • If you don't feel qualified to do this yourself, have a certified HVAC technician come out to test the unit for you.
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Section 3 of 7:

Diagnosing the Problem

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  1. “Leaking refrigerant can significantly reduce the efficiency of your AC unit,” Belavus explains, “So if you feel like your AC is producing less cold air than usual, try measuring the temperature output. The normal cooling temperature should be somewhere between 40-50°F.” However, a broken thermostat may cause the same problem. If it’s a refrigerant issue, the air temperature will steadily grow warmer over time because your unit is slowly losing refrigerant.
    • If a broken thermostat or other issue is causing the warm air, the temperature of the air will probably spike or fluctuate.
  2. According to Belavus, “Any signs of ice forming on refrigerant piping could indicate a refrigerant leak.” Peek through the front window of the AC unit to inspect the pipes inside. If the pipes and coils look frosty or ice-covered, this means you’re experiencing a leak and slowly losing refrigerant. The leak needs to be repaired by a qualified HVAC technician or you’ll continue to experience the same problem.
    • Adding refrigerant without fixing the leak may further damage your AC unit.
  3. Inspect the area around your furnace. If you see water pooling around it, this indicates condensation. Your coils were most likely icy, and now the ice has melted around the furnace area. Additionally, Belavus explains, “Check around the indoor air handling unit and outdoor condenser for any signs of oily, dark spots, especially on the coils. Look for oily stans on refrigerant pipe insulation.”
    • The water can damage your furnace and compound your problems, so it’s best to have a qualified HVAC technician come out to inspect the issue.
  4. AC units are sealed tightly, and the Freon should never leak. If you need to refill refrigerant, you probably have a leak . “If you suspect that your AC unit is leaking refrigerant, it’s important to have it inspected by a licensed HVAC professional as soon as possible to prevent further damage to the unit and ensure that it is functioning properly,” Belavus explains.
    • Adding more refrigerant is a quick fix, but eventually, this will damage your unit.
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Section 4 of 7:

Can I add Freon to an AC unit myself?

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  1. It’s best to hire a professional HVAC technician to add Freon. While it technically isn’t illegal to add some refrigerants yourself, the job is very dangerous. Adding refrigerant incorrectly can damage your AC unit, while handling it improperly can lead to injury or even death. For this reason, it is highly advised that you hire a professional. It is also illegal to handle R-22 Freon without a license, so determine what kind of refrigerant your AC requires before attempting to do it yourself. [13]
Section 5 of 7:

How often does Freon need to be replaced?

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  1. Freon only needs to be replaced if your air conditioner has a leak. Because Freon circulates inside your AC unit in a closed loop, you ideally shouldn’t have to replace it. However, if the coolant pipe has a leak, the Freon will seep out, and you’ll need to replace what you’ve lost. [14]
    • Some signs your AC is leaking refrigerant include having ice on the evaporator coils, making a hissing sound, and giving off an exhaust smell.
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Section 6 of 7:

How much does it cost to add Freon?

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  1. Adding Freon costs anywhere from $100-$600. The cost of adding Freon to your AC largely depends on the unit’s size. Adding refrigerant typically costs between $100-$350, though it may cost up to $600 for large units, as they require more refrigerant. R-22 refrigerant costs $80-$120 per pound, while R140A usually costs around $20 per pound. [15]
Section 7 of 7:

How to Prevent Refrigerant Leaks

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  1. Have your unit professionally serviced at least once a year. Regular maintenance is key to keeping your AC in good working condition. A professional HVAC technician will look for signs that a leak may happen and make the necessary repairs to prevent or fix it. They’ll also top off your refrigerant if it is below the necessary level. When getting your AC serviced , Belavus recommends, “Try to remember your service history and let the tech know if there are any pre-existing conditions with the system.”
    • If you can’t get your AC serviced every year, Belavus says, “It’s important to get it professionally serviced at least every other year for better efficiency and greater lifetime.”
    EXPERT TIP

    Victor Belavus

    Air Conditioning Specialist
    Victor Belavus is an Air Conditioning Specialist and the Owner of 212 HVAC, an air condition repair and installation company based in Brooklyn, New York. In addition to HVAC and air conditioning units, Victor also specializes in furnace repair and air duct cleaning. He has over 10 years of experience working with HVAC systems.
    Victor Belavus
    Air Conditioning Specialist

    Don’t do extensive maintenance yourself. The most important thing for any household owner to do is to replace AC filters regularly, at least every 3 months, and inspect the outdoor condenser for any debris. I would also recommend covering your condenser for the winter to protect it from snow.

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      Warnings

      • Because handling refrigerant is extremely dangerous (and in some cases, illegal) it is highly recommended that you hire a professional HVAC technician to refill your AC unit rather than attempting to do it yourself.
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      References

      1. ↑ https://todayshomeowner.com/hvac/guides/how-often-to-add-freon-to-ac-unit/
      2. ↑ https://todayshomeowner.com/hvac/guides/how-often-to-add-freon-to-ac-unit/
      3. ↑ https://www.epa.gov/snap/refrigerant-safety
      4. ↑ https://www.hvac-for-beginners.com/air-conditioner-charging.html
      5. ↑ https://www.mitchwrightair.com/blog/2017/june/how-to-add-freon-to-your-central-ac-unit/
      6. ↑ https://youtu.be/J1s4wxDBe24?t=108
      7. ↑ https://youtu.be/J1s4wxDBe24?t=148
      8. ↑ https://youtu.be/J1s4wxDBe24?t=253
      9. ↑ https://youtu.be/OSpfBXhk0nQ?t=471
      1. ↑ https://www.thetrainingcenter.com/epa-608-how-to-use-gauges-properly
      2. ↑ https://youtu.be/OSpfBXhk0nQ?t=749
      3. ↑ https://www.epa.gov/sites/default/files/documents/RealZeroGuidetoGoodLeakTesting.pdf
      4. ↑ https://todayshomeowner.com/hvac/guides/how-often-to-add-freon-to-ac-unit/
      5. ↑ https://todayshomeowner.com/hvac/guides/how-often-to-add-freon-to-ac-unit/
      6. ↑ https://todayshomeowner.com/hvac/guides/how-often-to-add-freon-to-ac-unit/

      About This Article

      Article Summary X

      Before you add Freon to an AC unit, make sure to clean the air filter, blower wheel, and coils to ensure your unit is running smoothly. Then, put on some gloves and safety glasses to protect yourself from the Freon and turn off your AC. After it is off, hook up the refrigerant gauges to the valve connections. Turn the AC back on and wait 15 minutes so you can get an accurate reading on the gauge. Then, twist the spout of the bottom of the canister to open the refrigerant and let it fill until you reach the target subcooling temperature To learn how to stay safe while using Freon, keep reading.

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