Why is my Air Conditioner Leaking Water?

Summertime is here, which means air conditioners (ACs) are running full blast to keep us cool. But what happens when your AC starts leaking wafter? Don’t worry; you’re not alone. An AC leaking water is a common problem. 

If you’ve been noticing water leaking from your air conditioner, it’s probably just a sign that something needs to be cleaned or fixed. Dirty filters and clogged drain lines are the most common culprits, but more extensive issues could cause leaks too. 

This article will walk you through the most common causes of air conditioner leaks and how to fix them. Keep reading to learn more.

water leaking from an air conditioner

Is Water in an AC Unit Normal?

The short answer is yes, AC units produce water. Air conditioners work by using a refrigerant to cool the air inside your home. Cold refrigerant runs through AC coils, and warm air blows across the cold coils. This removes the heat from the air (i.e., it cools the air), and then the blower circulates it throughout your home. 

Since warm air holds more moisture than cold air, water condenses onto the cold coils when its temperature drops. It then drips into a drain pan, leaving your home through the condensate drain line. 

The drain line empties into either the side of your house or into a sump pump. Depending on where your air conditioner is located, it may drain by gravity or require a condensate pump to remove the water from the drain pan. 

Note: So, if you see water dripping from your AC unit, that’s actually a good sign! It means your AC is doing its job. However, if there’s more water than usual or water leaking from other parts of the AC unit, that’s not normal and indicates a problem.

What Causes Air Conditioners to Leak Water

a person removing a dirty, clogged ac filter

There are several reasons your AC unit may be leaking water. Here are the most common causes:

Clogged Filter

One of the most common reasons for AC leaks is a clogged HVAC filter. Your AC unit needs clean filters to function properly and move air around your home. Dirty filters make your AC work harder, leading to several problems, including water leaks. 

To prevent this, check your AC filters monthly (more often if you have pets or live in a dusty or polluted area). If you have disposable filters, replace them every one to six months (depending on the filter). If you have reusable filters, wash them in warm soapy water and let them air dry completely before putting them back in the AC unit. 

Clogged Condensate Drain Line

Another common reason AC units leak water is a clogged condensate drain line. The drain line carries water away from the AC unit to a sump pump or outside your home. If the condensate drain line becomes clogged, water can back up and cause leaks. 

A build-up of dust, hair, mold, mildew, and algae is typically the cause of blockages in the condensate line. You can prevent clogs in your drain line by keeping your filter clean. 

There are a few ways to clean a clogged AC drain line:

  • Use a wet/dry vacuum to suck out any debris blocking the line. 
  • Pour vinegar or bleach down the drain line to dissolve any buildup. 
  • Remove the AC unit’s access panel and clean the drain line with a brush (you may need a long-handled brush to reach the end of the line).

You may have to try all three methods to clear the drain line. 

Note: If you have an older AC unit, the drain line may be made of plastic. Over time, these lines can become brittle and crack, which can also cause leaks. If this is the case, you’ll need to replace the entire drain line. 

Failed Condensate Pump

If your AC unit has a condensate pump, it may be failing. These pumps remove water from the AC unit when gravity can’t do the job. If the pump fails, water will back up and cause leaks. 

A failed condensate pump usually needs to be replaced. However, you may be able to clean or repair the pump if you’re technically inclined. If not, call an HVAC technician for assistance.  

Unlike central AC units, ductless mini splits are usually mounted high and drain via gravity. On the other hand, a central AC unit with the indoor unit in the basement almost always has a condensate pump (if it is pumping outdoors). 

You should also check the manufacturer’s manual for AC condensate pump maintenance tips. They may suggest lubrication or replacing gaskets at specific intervals. 

Corroded or Damaged Condensate Pan

The pan underneath your AC unit collects water that drips from the coils. If the pan is cracked, rusted, or otherwise damaged, it may leak. 

You can check the condition of the pan yourself by removing the AC unit’s access panel and taking a look. If the pan is damaged, you’ll need to replace it. The condensate pan is directly under your evaporator coils and looks like a shallow baking sheet. 

Refrigerant Leak

a HVAC technician adding more refrigerant

Another potential cause of AC leaks is a low refrigerant level. The refrigerant is what cools the air inside your AC unit. If there’s not enough refrigerant, the AC unit won’t be able to cool your home correctly. This can cause water to leak from the unit. 

If you suspect your AC unit has a low refrigerant level, it’s best to call a professional AC repair technician. They’ll be able to safely add more refrigerant to your AC unit and fix the cause of the leak.

Frozen Coils

Frozen AC coils are another common cause of AC leaks. The coils help remove heat from the air inside your AC unit. If they freeze, the AC unit won’t be able to work properly, and water can leak from the unit. 

There are a few reasons why your AC coils may freeze:

  • The AC unit is low on refrigerant 
  • The temperature outside is too cold 
  • The AC unit’s blower isn’t working properly 
  • Debris is blocking the AC unit’s airflow (clogged filter or blocked return vents)

If you suspect your AC coils are frozen, turn off the unit and call an AC repair technician. They’ll be able to diagnose the problem and make the necessary repairs. 

Worn Out AC Unit

Eventually, all AC units wear out and need to be replaced. If your air conditioning unit is more than ten years old, it may be time for a replacement. Older AC units are more likely to leak water because they don’t work as efficiently as newer ones. If you do replace your AC, a more energy-efficient AC model can also mean up to 40% energy savings. 

When an AC unit leaks water, it’s often a sign that it’s reached the end of its lifespan. If you’ve tried all of the other repair options and your AC system is still leaking, you may need to replace it. 

A qualified HVAC professional can assist you with determining if you need a new air conditioner or if yours is repairable. 

What to do When Your AC Unit is Leaking Water

a person using a garden hose to clean an AC system’s clogged coils

If your air conditioner is leaking water, turn it off. You can simply turn your thermostat to the “off” setting, unplug the AC unit from the wall, or turn off its circuit breaker in your breaker box. 

Once it is off, look through the list of causes we provide above and attempt to fix it or call one of our approved HVAC technicians for help. 

You will also want to clean up any water that spilled over the drain pan to prevent mold, mildew, and water damage. If you have a leaky portable AC unit, we recommend unplugging it and then putting it in a tub or over a drain to prevent water in unwanted areas in your home. 

Prevent Future Leaks with Routine HVAC Maintenance 

The best way to prevent AC leaks is with routine HVAC maintenance. AC units should be serviced at least once a year by a qualified HVAC professional. 

During routine AC maintenance, the technician will inspect your AC unit for potential problems and make necessary repairs. This can help prevent AC leaks (and other AC problems) before they start. 

In addition to AC maintenance, you can also help prevent leaks by following these air conditioner tips:

  • Regularly change your AC filter 
  • Keeping your AC coils clean 
  • Clearing debris from around the outdoor portion of your AC unit
  • Ensuring proper airflow around your AC unit 

By following these tips, you can help keep your AC unit in good working condition and prevent AC leaks. 

Don’t Cry Over Spilled AC Water

AC units leak water for a variety of reasons. The most common causes are a cracked condensate pan, low refrigerant levels, frozen coils, and a worn-out AC unit. If your AC unit is leaking water, turn it off and call a qualified HVAC repair technician. Routine HVAC maintenance can also help prevent AC leaks.

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Jonathon Jachura
Jonathon is a mechanical engineer with over ten years of experience in the HVAC industry. He has hands-on experience with all types of HVAC systems.

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