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 a water leak… except maybe moldy carpet, which happens to be the #1 Googled household fear (1). 

Both leaks and mold can be caused by an AC leaking water. And if you’re here, chances are your air conditioner is leaking and you want to know how to fix it.

If you don’t do something about it, AC water leaks can be a pricey and time-consuming fix. 

But don’t worry—you’ve found Sealed, and we kinda nerd-out on finding solutions to get your AC unit running as efficiently as ever. 

Ready? Let’s dig in.

Table of contents

If you’re just looking for a quick Q&A, we’ve got you covered. Tap here: FAQs about water leaking from AC systems 

Key Points:

  • A little bit of water dripping from your air conditioning system can be normal while it’s running, but full-on leakage is a serious issue that you shouldn’t overlook—ever
  • An AC unit leaking water might just need a good DIY cleaning, especially if your system hasn’t had regularly scheduled HVAC services. But it also can be a sign in older units that it might be time to search for a replacement.
  • Replacing your old, leaky AC with an energy-efficient HVAC system will make your home more comfortable and stop energy waste (win-win!). In fact, with a few other whole-house upgrades like insulation and air sealing (at no upfront cost), you could cut your energy use by 50%. Find out how.

Why is my AC leaking water? 

It’s actually normal for AC units to drip a little bit of water while they’re running. A few factors—like the time of year, humidity levels, and temperature—affect just how much your AC unit drips. 

But when is dripping water considered a leak? Well, your AC should never leak water when it’s turned off. That’s a huge warning sign and shouldn’t be ignored.

At their best, AC leaks can cause stains and not-too-minor damage. And at their worst? HVAC water leaks can cause dangerous after-effects like electrical and insulation issues. Leaks can also spark mold and mildew problems, which can cause serious illness in humans and pets.

Let’s address the leak head-on by troubleshooting together, starting with the five most common causes your AC unit could be leaking:

  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

Since it’s normal for your AC to lose small amounts of water during use, a drain line directs the dripping water (called condensate—a fancy word to describe humidity that turns to condensation, i.e., water) outside of the unit, into a drain pan. 

But if you have a damaged or rusted drain pan, you could have an AC leaking water inside the unit where you don’t want it. 

Cause 2: Clogged condensate drain line

If your drain pan is in good working order, the problem could be the drain line. Sometimes drain lines get clogged, which causes the condensate to find another escape route (aka leak!).

Cause 3: Air filters

Experts recommend changing air filters at least every three months because a dirty filter blocks air from your AC’s evaporator coils, causing them to freeze. When the coil-ice melts—you guessed it—you’ve got leaking water inside your AC.  

heat pump install
Scheduling a tune-up every year with an HVAC technician can help lengthen the life of your system.

Dirty filters can also lead to a stale and stuffy house. This is not your friend—especially if you’re getting whiffs of stale-smelling, hot air (lack of fresh airflow might cause a mildew or mold problem). 

Cause 4: Frozen evaporator coils

Dirty air filters aren’t the only culprit when it comes to frozen evaporator coils. Damaged or obstructed ductwork and low refrigerant can also cause the coils to freeze, which leads to a water leak when melted.

And take note: If your refrigerant levels are 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 super-important to make sure you have enough refrigerant.

(Have old, leaky ductwork—or no ductwork at all? Don’t fret. A ductless mini-split ac heat pump is an option for homes that don’t want to install or repair old ductwork.)

Cause 5: Broken condensate pump

Some AC units use good ole gravity to move the water through the drain line to the drip pan. But sometimes, HVAC systems need a little help from a condensate pump.

If your condensate pump isn’t working properly (maybe the float switch is broken), it will cause an AC leak. Or, sometimes the pump motor needs to be replaced, a fix that will cost upwards of $450. 

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

Back to top

How to stop an AC from leaking 

If your AC is leaking water, turn it off (and quick!). Don’t let one problem lead to another, like soggy flooring and drywall or, even worse, mold and mildew. 

So let’s delve into the best ways to fix your air conditioner that’s leaking water.

Let’s start with some DIY fixes.

frustrated homeowner uses HVAC thermostat guide to turn off an AC leaking water
Important: Turn off your AC unit before you start any DIY repairs or cleaning.

Clean up time

Once you’ve shut down your AC, it might be time for a hearty cleaning. 

These two spots are pretty easy to tidy up:

  1. Compressor Fan: The condenser unit, where you’ll find the fan, is in the outdoor unit, and you’ll need a screwdriver or drill to remove the panels first. 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 dry vac, you can use that as well, but be sure not to damage the fins. 

If these do-it-yourself cleanings sound complex, don’t worry! Deep-cleaning the inside of an AC unit is usually left to the pros. (In fact, scheduling a tune-up every year with an HVAC technician can help lengthen the life of your system.)

What if your AC is on its last leg? Even a well-maintained AC unit won’t last forever. Eventually, you’ll have to part ways and replace it. Learn the 7 signs that it’s time for an HVAC upgrade

Replace your AC

If troubleshooting reveals one too many problems with your air conditioner, it may be time for a new one. Find out how long AC units last and when to replace your HVAC system.

And if it’s time to replace yours? See if your home qualifies for a super-efficient heat pump HVAC upgrade at no upfront cost with Sealed.

(Yes, you read that right. And if you don’t save energy, we take the hit.)

Back to top

The best HVAC for replacing a 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). 

Your HVAC appliances are the biggest energy wasters in your home—especially when they’re not working properly. 

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

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


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

Tap here to complete our 2-minute questionnaire to see if your home qualifies for a heat pump upgrade—at no upfront cost. 

I wouldn’t hesitate to recommend Sealed for HVAC and insulation upgrades. If you’re looking to take on a large efficiency project for your home without the large upfront cost, Sealed is worth a look.

Matt R., Sealed customer
worker air sealing ductwork in attic using spray foam

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

Replacing your old AC might fix your water leak, but to keep your new HVAC in tip-top shape, you should probably address the other leaks in your house: air leaks.

Quality air sealing and insulation will help your AC work more efficiently and lengthen its lifespan. Plus, it can help keep your home dry, evenly cool the upstairs of a 2-story home, and boost your indoor air quality—all while saving on energy bills.

In fact, you could cut up to 45% of your energy waste in your home with the right air sealing and insulation upgrades alone (5). Check out our guide to air sealing and attic insulation guide to learn more.

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

Are you stuck in the “repair vs. replace” decision vortex?  We can help you make the right choice for your home.

You could get top-of-the-line, energy-efficient heat pump AC upgrades… and finally say farewell to your vintage AC system.

It starts with a 2-minute questionnaire.  

white new construction home with heat pump outdoor condenser
Heat pumps can be up to 3 times more efficient than traditional HVAC systems.

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

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.

We’ll do all the heavy lifting to make your house feel great. Find out if you qualify today.

Back to top

Frequently asked questions about leaky air conditioners 

Use this list to jump ahead to the question you need answered today.

Don’t see your question here? Call us. We’re here to help.

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

If your AC is leaking water, 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. Tap here to find out why.

How do you clear an AC drain pipe?

A clogged air conditioner drain line can lead to a water overflow problem in your drip pan, damaging your AC. 

To clear the line, locate your drain pipe (attached to the wall near the condenser unit outside). Now remove the cap to the access point and look for the blockage.

You may be able to clear the 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 clog. 

Here’s how to spot it:

  1. Small pools or puddles of water around the indoor or outdoor unit
  2. Water damage around your house 
  3. 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 four times a year—or every three months. 

How much does it cost to clean an AC drain line?

Clogged drain line repair runs from $75 to $250 (6), which is a whole lot cheaper than a full evaporator coil replacement, which can run from $800 to $2,400 (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 metal, so it’s best to use vinegar whenever possible. Safety tip: Do not use both vinegar and bleach. These two household chemicals should never mix.

Safety tip: Do not use both vinegar and bleach. These two household chemicals should never mix.

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 vac, 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 wet vacuum to get rid of any standing water around your drain pan. After that, you can use the dry vac 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, 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 that doesn’t work, try these troubleshooting tips or call in an HVAC expert. 

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 (answer our quick questionnaire 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