How to Check the Freon in a Home Air Conditioner

Presidential Heating & Air Conditioning

Gaithersburg HVAC Contractors


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a man learning to check the freon in a home air conditionerAs the weather gets warmer, many homeowners start to question if their air conditioner is working its best. You might start to wonder if your home should be cooler, or if your AC unit is working properly. That said, many homeowners neglect to check their AC unit’s Freon levels. Knowing how to check the Freon level in your home air conditioner unit and what repairs may need to be made, can make your summer nights a bit more comfortable, while saving you time and money by determining the issue yourself. In this brief guide, learn a little about what Freon is and what you can do to check your home air conditioner’s Freon levels.

What is Freon?

In order for the air conditioner to do its job and cool the air, it needs a refrigerant or coolant that will actually cool the air in your AC unit. That is the role of Freon, the most common cooling agent found in air conditioning units.

Freon is crucial to the performance of any air conditioner, but you do not want to handle Freon issues yourself. Freon is known as chlorofluorocarbon(CFC), which has been tied to ozone depletion and is highly toxic. Inhaling high concentrations of Freon can cause breathing problems, fluid buildup in the lungs and organ damage. For these reasons, Freon is currently being phased out of use in most AC units, and should really only be handled by professionals. That said, there are safe ways to check your Freon levels and ensure that the refrigerant is causing the problem with your AC unit.

Common signs Freon is Low

You want to be confident your AC unit needs a refill of Freon because there are also other issues that could be inhibiting your AC’s performance. You want to rule out any of those other issues before arranging for a refill. There are a few signs to look out for that will indicate your Freon is low.

Blowing Warm Air

If the Freon is low, your air conditioner will start to blow warm air instead of cold air. You can very easily detect if this is happening by just placing your hand in front of the vent and determining the temperature of the air. You will also be able to tell your unit is blowing warm air if your AC is running all day but your home is still warm.

Hissing Noise

person fixing the home air conditioner to check the freonWhile small leaks will not give off a noise, large leaks will, and that noise will typically sound like hissing or bubbling. If you hear that type of sound, you likely have a Freon leak. You will want to get that leak repaired before refilling or recharging the Freon. Having the Freon refilled without repairing the leak will not solve the problem and you’ll likely be back to where you started in a short time.

High Energy Bills

If you are paying higher energy bills than normal, or if it seems your AC unit is constantly running, it is likely that your Freon needs to be refilled. If your unit was performing properly, you wouldn’t need to have it running around the clock.


Because of the low refrigerant, moisture on the outside of your AC unit will freeze and build on the outside of the unit along the refrigerant lines. This is yet another sign of low Freon.

Checking Freon Levels (what is considered low)

A few different ways to assess your AC unit’s Freon levels on your own include the following tests:

  • Sound Test: If your AC unit is giving off a hissing or bubbling sound, it is a good indication your Freon levels are low. You can determine where the sound is coming from by listening to all points along the line. Again, you will only hear a hissing or bubbling sound if the leak is substantial.
  • Soap Test: This method of checking for a leak in your AC is one of the oldest, yet most reliable. You simply put a mixture of water and soap where you think there might be a leak. If there is coolant escaping in that location, you will see your mixture bubble up. While this is a very reliable method, it really only works if the leak is substantial. If it is very small, you aren’t likely to see any bubbling.
  • Detecting Electronically: You can purchase a sniffer, which is basically an electronic detector that will check for leaks in your AC unit. There are a lot of different models of these sniffers available, but keep in mind they are not always totally reliable in detecting leaks.

There are a few other ways to assess the performance of your air conditioner that don’t involve Freon, such as:

  • Filter: The air filter on any air conditioning unit can easily become clogged. You can make sure they are clean and not blocked. Sometimes a good cleaning of the air filter can get your AC unit back up and running properly.
  • a woman confused about how to check the freon in her home air conditioner

  • Fan: A quick inspection of the fan is pretty easy to do. You simply put the AC unit on and then take a look at the fan. You want to make sure the fan starts automatically. If it doesn’t, there might be an issue with the motor.

If none of these maintenance measures or checks for low Freon help you uncover the issue, chances are that your Freon needs to be refilled. If you are not confident about checking your AC’s Freon levels or think you need a more in-depth evaluation, we recommend reaching out to the HVAC Contractors at Presidential Heating and Air. Schedule a free consultation with them today to quickly assess if you need to refill the Freon in your home AC unit.

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