AC Freon Leak – What Causes Them?

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Updated February 2, 2023

Even the best air conditioners run into common problems that have to be dealt with from time to time. For example, you might encounter a refrigerant leak, which is something you need to handle immediately. Freon is a dangerous chemical that can be physically harmful. The main cause of freon leaks is small holes created in the evaporator coils created by erosion. The erosion is caused by rust or acid, and such leaks can be dangerous. On the other hand, if your air conditioner is leaking water, this is easier and safer to resolve


  • Coolant leaks are caused by erosion on the evaporator coils and are a severe problem that lowers the unit’s effectiveness and raises energy costs.
  • A refrigerant leak is dangerous to inhale and to touch. Any leak must be dealt with immediately.
  • To prevent leaks, schedule regular maintenance and check that refrigerant levels are not too high or low.

Understanding AC Freon Leaks

Air conditioner refrigerant (or Freon) is a chemical compound vital to any functioning air conditioning system’s cooling process. The refrigerant passes between the main components of an air conditioner. It’s the substance that transfers and expels heat as it passes over the evaporator coil system.

Keep reading as we explain what causes freon leaks, how to look for them, and what you can do to prevent them from happening.

Alternatively, for more material on AC-related topics, you can check out our article on what air conditioner filters do.

Insider Tip

It’s best to hire a professional to charge your AC because the potential costs of getting it wrong yourself outweigh the maintenance charge.

But you don’t have to be an expert on the internal mechanics of a cooling system to know that chemical leaks are no joke. You might be able to refill freon in a window air conditioner, but for central units, those are tougher. Even if you’re just trying to figure out the compressor on an air conditioner, it’s always harder on a central A/C. Below, we’ll explain how to tell if you have a freon leak.

And if you are looking to do some DIY repairs, check out our guide on how to change the power cord on a window AC unit.

How to Spot a Refrigerant Leak

A handful of telltale signs point to an AC Freon leak. If one or more of the signs below are happening, call a service company to come to look at your air conditioning unit. This is likely one of the reasons your A/C hiss.

  • Increased Utility Bills
  • Hissing Sounds Coming from Your Unit
  • Decrease in Cooling Power
  • Increase in Indoor Humidity
  • Iced Over Evaporator Coils

STAT: Because the United States has decided to phase out R-22 refrigerant, prices have gone up, and it can be hard to find. (source)

How to Prevent Freon leaks

The best way to ensure your unit is free of coolant leaks is to have routine maintenance inspections. Having an air conditioning repair company look at your unit catches issues before they become dangerous. Or, if the unit is rust-resistant like the one in our Portacool PACCYC06 review, you can avoid those erosion holes developing that way.

Another prevention measure is always to make sure you have the proper refrigerant levels. Having refrigerant levels that are ‌too high or too low is dangerous and can damage your unit. So whenever an HVAC professional is looking at your unit, be sure to have them check the level to ensure it’s right where it should be.


How do I know which type of refrigerant is right for my AC unit?

To check the type of refrigerant, look at the label or sticker on the window/portable unit or outdoor condenser. This label should indicate what kind of refrigerant your unit takes.

Is it ok if your AC leaks a small amount of water?

While the unit is running, a little condensation water is normal and is no cause for concern. However, have a maintenance expert check this out if the water gets excessive or leaks while not running.

What do I do if my AC’s refrigerant levels are low?

You may need a refrigerant charge if you suspect your levels are low or notice that your evaporator coils are icing over and your electricity bills are rising.


Using the wrong refrigerant in your air conditioning system will cause damage, sometimes irreversible damage, to your air conditioning unit.

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