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Why is my AC leaking water? And how do I fix it?

No one likes seeing water where it’s not supposed to be. Get to the heart of a leaky AC in this guide—and then get back to enjoying your home.

No one likes seeing water where it’s not supposed to be. Get to the heart of a leaky AC in this guide—and then get back to enjoying your home.

Not many things are as alarming for homeowners as water mysteriously dripping inside… except maybe molded carpet due to a flood or leak, which happens to be the #1 Googled household fear (1). 

What do these two things have in common? Well, both can be caused by an AC leaking water. 

If left too long, AC water leaks can be a pricey and time-consuming fix. 

So let’s dig into why your AC is leaking water, and finally figure out how to fix it. (That way, you can get back to enjoying your house!)

You’ll get answers to the following questions:

We’ve also included a section covering FAQs about water leaking from A/C systems if you’re looking for a quick Q&A. 

What makes an AC leak water? 

Believe it or not, it’s normal for AC units to drip a little bit of water in the cooling process. And there are a few factors—like the time of year, humidity levels, and temperature—that affect just how much your AC unit drips. 

The real question is, when is dripping water considered a leak? Well, condensed water from your outdoor unit will drip whenever your AC unit is running. But your AC should never leak water when it’s turned off. 

Whatever you do, don’t ignore when your air conditioner leaks water from the wrong place—or at the wrong time. HVAC water leaks can lead to some dangerous after-effects like electrical and insulation damage. And let’s not forget that leaks can spark mold and mildew problems, which can cause serious illness in humans and pets. 

The inner workings of an AC can be complex, especially if you’re trying to troubleshoot a problem. Learn the 7 signs that it’s time for an HVAC upgrade

Ultimately, there are a few reasons your AC unit could be leaking water. Let’s troubleshoot together by looking at the five most common causes:

  1. A damaged drain pan
  2. A clogged drain line
  3. An air filter issue
  4. Frozen evaporator coils
  5. A broken condensate pump

Cause 1: Damaged drain pan

Primary AC drain pans are located below the evaporator coils and work with the drain line to lead any runaway liquids outside. If your drain pan is rusted or damaged in any way, it can cause water leaks where you don’t want them. 

Cause 2: Clogged drain line

Drain lines are connected to drain pans, and when they’re working correctly, they carry condensate (which is a fancy word to describe humidity that turns to condensation, i.e., water) from your indoor unit back outside. But if you have a clogged drain line, dirt, debris, or even algae could keep it from doing what it’s supposed to do.

Cause 3: Air filters

Did you know air filters can cause leaking water in your air conditioner? It’s true! A dirty filter blocks air from your AC’s evaporator coils, causing them to freeze. The drain pan overflows when the coil ice melts, and there you have it—leaking water in your AC.  

Experts recommend changing air filters at least every three months. But in the summer when your air conditioner is working overtime, you may need to check your filter monthly.

Cause 4: Frozen evaporator coils

As long as there’s enough airflow from inside your house to blow over the cold coils, you’re good to go. 

But if there’s not enough—either due to a bad air filter or ductwork problems—it can cause your evaporator coils to freeze. Then when your AC turns off, the coils melt, which leads to a water leak. 

Now, there’s another way evaporator coils can freeze, and that’s if there’s not enough refrigerant. Low refrigerant levels can also cause AC units to become too cold and freeze.

And if your refrigerant is low due to a freon leak, it could be dangerous. Inhaling freon is a health hazard and can lead to serious illness, so it’s important to make sure your refrigerant levels are up to snuff.

Cause 5: Broken condensate pump

Condensate water drains when air passes through the cold evaporator coil during the cooling process. Some AC units use good ole’ gravity to help move the water out. But sometimes, HVAC systems need a little help from a condensate pump.

If you notice water around your AC, you might have a broken condensate pump. Maybe the float switch that energizes the pump is broken or the pump itself has motor issues (a replacement can cost upwards of $450). 

Looking for home heating and cooling upgrades at no upfront cost? See if your house qualifies.

How to fix a leaking air conditioner 

If your AC is leaking water, the first thing you need to do is turn it off. And, quick! 

When AC units leak water, depending on where your unit is located (and how much water it’s leaking), it can ruin flooring and drywall, or even worse, be a hotbed for mold and mildew. 

frustrated homeowner uses HVAC thermostat guide to turn off an AC leaking water

So let’s delve into the best ways to fix your air conditioner leaking water, from DIY tricks to when you should call an HVAC professional.  

Let’s start with the DIY fixes.

Clean up time

Once you’ve shut down your AC and done a bit of troubleshooting, it might be time for a hearty cleaning. 

Here are two of the easier spots to tidy up:

  1. Compressor Fan: The condenser unit, where you’ll find the fan, is on the outdoor part of your AC.  You’ll need a screwdriver or drill to get the panels out of the way. That should reveal exactly what you might expect—a whole lot of dust and dirt. 

    Experts recommend a soft bristle brush for cleaning. Once you’ve scrubbed (and scrubbed), put the panels back on.
  2. Evaporator coils:  The evaporator coils are on your indoor unit behind the access door. You’ll be able to open the door by removing the screws. Brush the coils with a nylon brush from top to bottom. If you have a vacuum, feel free to (carefully) use that as well, but be sure not to damage the fins. 

Pro tip: Replace your air filters. It’s the quickest and most budget-friendly prevention tool to keep dirt and dust from building up in your AC unit all over again. 

If these do-it-yourself fixes sound complex, you’re not alone! Deep-cleaning the inside of an AC unit is usually left to the pros. (In fact, scheduling an HVAC tune-up every year can help lengthen the life of your heating and cooling gear.)

What if your AC is on its last leg? If it hasn’t received regularly scheduled maintenance and is getting close to its teenage years, you might be in the “repair vs. replace” relationship stage with your air conditioner.

Replace your AC

If your troubleshooting reveals one too many problems with your air conditioner, it may be time for a new one.

See if your home qualifies for heat pump HVAC upgrades at no upfront cost with Sealed.

(Yes, you read that right. You pay us back for the work done for energy-efficient HVAC home upgrades based on a rate of the energy you save. If you don’t save energy, we don’t get paid.)

white new construction home with heat pump outdoor condenser

The best HVAC system for replacing a broken or leaking AC? An air-source heat pump. 

Did you know that 51% of your home’s energy use is for heating and cooling alone? (2). 

How much of that energy used is helping you stay comfortable, and how much is actually being wasted?

Your HVAC appliances are the biggest energy wasters in your home—especially when your air conditioner or heater isn’t working properly. 

(Find out how you can stop energy waste at home.)

Traditional HVAC systems make up more than half of your home’s energy use, but if you make the switch to a heat pump, they can be up to 3 times more efficient (and they replace both with one appliance—heat pumps both cool your home in summer and heat it in winter). (3)

And 81% of heat pump users feel an increase in comfort when they make the switch (4).

Heat pumps are a smarter, cleaner, more efficient way to heat, cool, and dehumidify your home. 

Learn how heat pumps work—and why they’re so energy efficient.

(Have old, leaky ductwork—or no ductwork at all? Don’t fret. There are even ductless mini split ac heat pump options for homes that don’t want to install or repair old ductwork.)

Take the 2-minute quiz to see if your home qualifies for a heat pump upgrade—at no upfront cost. 

You could cut up to 50% of your energy use when getting high-performance insulation, professional air sealing, and heat pump HVAC upgrades with Sealed.

How air sealing and insulating can help prevent HVAC overwork—and AC leaks 

If your AC is leaking water and isn’t working correctly, a stale and stuffy house is not your friend. Especially if you’re getting whiffs of stale smelling air—it could be a mildew or mold problem! 

Quality air sealing and insulation can help keep your home dry, evenly cool the upstairs of a 2-story home, and boost your indoor air quality—with the added benefit of helping your existing AC work more efficiently and lengthening its lifespan.

worker air sealing ductwork in attic using spray foam

In fact, you can save an average of 15% on heating and cooling costs when you seal and insulate (5). Check out our guide to air sealing and attic insulation guide to learn more.

Not for sure if you need to totally replace your AC or if a repair is needed? We’re here to help you make the right choice for your home. Talk to us—a call with Sealed is free.

Need to break up with your old AC? Get an energy-efficient heat pump at zero upfront cost.

It starts with a 2-minute quiz.  

You could get top-of-the-line, energy-efficient heat pump AC upgrades… and finally say farewell to your vintage AC system that’s on its last leg. (Not to mention, your house will feel amazing year-round and waste less energy, too).

If your house qualifies to work with Sealed, you can get customized HVAC, insulation, and weatherization upgrades to your home at no (or very little) upfront cost.

We’ll do all the heavy lifting to make your house feel great.

And we take all the guesswork out of finding trusted and vetted local professionals. We’ll negotiate pricing, manage the project, and make sure everything goes as planned.


Frequently asked questions about leaky air conditioners 

Use this list below to jump ahead to the question you need answered today, or feel free to scan ahead.

Don’t see your question here? Call Sealed at 888-985-7481. We’re here to help.

heat pump install

Can I still use my AC if it’s leaking water?

If your AC is leaking water right now, definitely turn it off. This means you’ll need to turn off the indoor AC, and disconnect the switch installed outside next to the air conditioning unit. 

Water leaks from your AC can lead to electrical damage, water damage, and even mold and mildew problems—which can be a pretty pricey fix!

How do you clear an AC drain pipe?

A clogged air conditioner drain line can lead to a water overflow problem in your condensate pan. And that can really damage your AC. So it’s pretty important that the drain pipe stays clear. But how? 

First, locate your drain pipe attached to the wall near the condenser unit outside. Now it’s time to locate the access point, which is covered with a cap you’ll need to remove. Look for the blockage.

You may be able to take out any build-up with your hands (wear gloves!). If not, pour distilled white vinegar inside the drain and leave it for about 30 minutes. Once the time is up, flush out the vinegar with water.  

How do I know if my AC drain is clogged?

When your air conditioner takes moisture out of the air, it sends that liquid to the AC unit’s condensate drain line. Over time, dirt and grime build up, which can cause a clogged condensate drain line. Here’s a few ways you can spot it:

  • Small pools or puddles of water around the indoor or outdoor unit
  • Water damage around your house 
  • A stale or moldy smell

How often should you clean the AC drain line?

Experts recommend cleaning your drain at the end of every season, so that’s about 4 times a year—or every three months. 

How much does it cost to clean AC drain line?

Clogged drain line repair can be anywhere from $75 to $250 (6). If your HVAC contractor finds you need a full evaporator coil replacement, that could cost you $800 to $2,400, depending on a number of factors (7).

Is bleach or vinegar better for AC drain line?

Bleach and vinegar, flushed with hot water, are some of the most common ways to clean your AC drain line. However, too much bleach can be bad for the metal parts of your air conditioner, condensate drain pan, and drain pipes. It’s best to use vinegar whenever possible.

How do you clean a condensate line?

If you’re planning to clean your condensate line, you’ll need a few supplies: a rag, a wet/dry vacuum, distilled vinegar, and a funnel.

Find the condensate pan in your indoor air handler (likely in your attic, basement, or utility closet). Then use a hand-held or shop vacuum to get rid of any standing water around your drain pan. After that, you can use a suction part of your vacuum to clear the clogged drain. 

Next, look in the vacuum’s canister to see if the blockage is gone. Find the point where you can get to the drain line and remove the T-shaped vent, then clean the drain by pouring vinegar down it. Give the solution half an hour to sit and then flush it with water.

How do I stop my air conditioner from leaking?

If your AC is leaking water actively, turn it off ASAP. Once you’ve done this, you can try cleaning up your compressor fan, evaporator coils, drain pipe, or drain line.

If the cause of your AC water leak is a bit more complex, it may be time to call in an HVAC expert. (You can get started by troubleshooting. Tap here to see our full list of tips.)

Wondering if you can get a customized HVAC fix for your house with Sealed? It’s absolutely possible to make your house feel amazing year-round.

If I don’t have to spend any extra money to get a huge improvement to my home, it’s just a no brainer at that point.

Scott R., Sealed customer

If your home qualifies to work with Sealed (take our quick quiz to find out), you could get energy-efficient heat pump AC, high-performance insulation, and professional air sealing at no upfront cost.

August 19, 2022