6 Signs You May Have an AC Coolant Leak and Tips to Prevent It

Paige Bennett
Written by Paige Bennett
Updated April 24, 2023
An AC on house backyard
Photo:-galinast / iStock / Getty Images Plus / Getty Images


  • Refrigerant enhances your AC’s cooling capacity.

  • Frozen coils, a warmer home, and higher electric bills can signal a refrigerant leak.

  • Barring any leaks, the refrigerant in an AC unit should last 10 to 20 years.

  • Contact a licensed professional to handle any leaks.

Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.

If your air conditioning system is taking a long time to cool down your home, it could be a sign that you have an AC coolant leak, often a Freon™ leak. But what is Freon™? It’s the most common HVAC refrigerant, a gas that’s essential for keeping your AC working and your home cool. Without it, your house can go from sanctuary to sauna in a heartbeat.

The coolant in your AC unit should last 10 to 20 years, but if there’s a leak, a pro needs to address the issue ASAP since these chemicals can cause refrigerant poisoning. Below, we’ll cover six signs of an AC coolant leak to be aware of so you can get on the path to repairing any damage quickly.

Note: Before you dive into the troubleshooting steps below, keep in mind that refrigerant is a dangerous chemical. Improper handling and inhalation of Freon™ or any other refrigerant can cause serious side effects, like asphyxiation and severe lung damage, according to the U.S. Environmental Protection Agency. If you’re not a certified professional, do not try to fix any coolant-related issues on your own. 

6 common signs of an AC coolant leak, including indoor humidity going up

1. Warm Air Coming From Your Vents

First and foremost, let’s get the easiest troubleshooting tip out of the way. Is it possible someone may have accidentally switched the setting on your thermostat to “warm?” You should also check if you have your AC set to “auto” rather than “fan.” The “fan” setting lets air blow through your vents even if your AC isn’t going through a cooling cycle.

If you’ve done multiple checks and the air isn’t as cold as it should be, you might have a refrigerant leak and should find a pro to help you with the issue.

2. Frozen Evaporator Coil

Having a frozen evaporator coil is another telltale sign you might have a Freon™ leak. Usually, the refrigerant passes through your indoor evaporator coil and removes heat from the air in your home during the cooling process. Then, it blows that hot air over the coil to prevent freezing.

To check for freezing, first, make sure you turn off your AC. Then, locate your evaporator coils, which are behind a removable access panel in your indoor unit. If you notice ice on your coil, get help from a licensed professional. If the problem is left to linger, you’ll have to pay between $600 and $2,000 to replace your evaporator coil.

3. Loud Hissing Noises

No, that hissing sound is not an unwanted snake living in your vents (although we won’t fault you if you want to double-check). This noise can signal various problems with your AC, but it’s usually the sign of a refrigerant leak caused by cracks in your coils. 

Inspect your indoor or outdoor unit for problem areas. Larger cracks or holes may sound like something is bubbling, which indicates refrigerant leaking from your system.

4. Higher Electric Bills

Have you noticed a recent spike in your electricity bills? If so, you’ve probably been trying to counteract the humidity by lowering the thermostat temperature. Combatting hotter temperatures while facing a leak means your air conditioner will have to work twice as hard.  

The inefficiency in your cooling solution is why your electric bill isn’t at its usual rate. Take some time to review your statements from the same time last year. If there’s a noticeable difference, it might be time to repair your AC. 

5. Increased Indoor Humidity

A natural function of your air conditioner is to dehumidify your home. But a lack of cooling capacity means your AC will have a tougher time removing hot air from your home.

Discomfort aside, your house may also become a breeding ground for dangerous mold and mildew. Put on a mask, long sleeves, and gloves, and break out the cleaning supplies to address any problem areas. Then, enlist the help of an HVAC specialist for further diagnosis and repairs.

6. AC Is Not Cooling Fast Enough

HVAC units rely on coolant to bring down the temperature of your home’s air passing through the system and to transfer heat from that air back outside. So if the refrigerant is leaking, the air isn’t getting cooled down sufficiently, and the heat transfer isn’t happening as efficiently. This can mean that your home feels warmer than usual, even when the AC unit is running.

If you try turning down the set temperature on the thermostat a couple of degrees but it doesn’t cool down your home quickly enough, you could be dealing with an AC coolant leak. But keep in mind that when the AC is not cooling fast enough, it could also be because of dirt or debris clogging the system or filter. You’ll need to do some AC troubleshooting to determine the problem.

What to Do When There’s a Refrigerant Leak

After you’ve confirmed one or more of the signs above, you’ll need to know what to do if the AC refrigerant is leaking. Refrigerant leaks may not seem like a big deal, and you may think about handling the issue on your own. However, this solution isn’t ideal because Freon™ leaks can harm your health and cause serious complications.

It’s best to seek a qualified AC repair specialist near you to tackle any AC coolant leaks. Most pros will charge between $50 to $150 per hour to service your system. Before setting up a visit, make sure to check your contractor’s references and credentials.

How to Prevent AC Coolant Leaks 

Once a pro has resolved any refrigerant leaks, you’re probably wondering how you can prevent this from happening again in the future. Luckily, some simple AC maintenance tips can go a long way in keeping your unit up and running.

Clean AC Coils

The evaporator coil and the condenser coil in an AC unit can get dirty. If that dirt and debris are left to sit on the coils for a long time, they can develop formic acid, which can then make holes in the coils and lead to a leak. Make sure to inspect and clean AC coils in your unit at least once per year to minimize this risk.

Replace Air Filters

So many AC issues can start with a clogged air filter. If you can’t remember the last time you replaced the AC air filter, it’s time to change it. You should replace your air filters at least once per month. If your AC unit has a reusable filter, you should clean the AC filter once per month.

Schedule Regular Inspections

The best way to keep your AC in tip-top shape and prevent an AC coolant leak is to get it tuned up from time to time. Regular AC tune-ups in the spring can ensure your refrigerant levels are not too high or low, the system is clear of any debris, and all the parts are in working order. 

Not only can this save you money each month on utility bills by keeping the system running efficiently and preventing AC coolant leaks, but annual inspections can also save you money on high-cost damages. That’s because an HVAC specialist will catch any damage or wear and tear early before it causes more serious and costly problems.

Conroy Baltimore contributed to this piece. 

Need professional help with your project?
Get quotes from top-rated pros.