Window Air Conditioner Droping Water (Causes & Fixes)

Window Air Conditioner Droping Water (Causes & Fixes)

Have you ever noticed water dripping from your window air conditioner outside?

You’re not alone. It’s a common problem that can be caused by many different issues. From clogged drains to low refrigerant levels, there are various reasons why window AC units might drip water outside.

In this blog post, we will explore some of the most common causes for window air conditioners leaking and what you can do to fix them. We’ll also discuss how to prevent window AC unit leaks in the future so that you don’t have to worry about dealing with this issue again!

So if you want to learn more about window air conditioner drips and what causes them, keep reading!

What is a Window Air Conditioner and Why Do They Leak?

What is a Window Air Conditioner and Why Do They Leak
Image Credit: everydaycheapskate

A window air conditioner is a cooling system built into the window of your home. It works by drawing in warm, humid air from outside and cooling it down before pushing it inside the room. This process requires condensation to occur, which is when water droplets form on the window unit’s evaporator coil as the AC draws moisture out of the air.

Sometimes, though, window air conditioners drip water outside instead of collecting it in a drain pan. When this happens, there could be any number of issues at play. No matter the issue, it will need to be fixed as soon as possible.

If you don’t fix the problem, it can lead to water damage and mold growth, which could be costly to repair.

Common Causes for Water Dripping Out of Window Air Conditioners

No one likes moisture dripping from their window unit, nor the damage it can cause to your personal and residential property. If you’re experiencing window air conditioner leaks, there are many common causes.

Here are a few to look out for:

1. Clogged Condensation Drain

One of the most common causes for window AC units leaking water is a clogged condensation drain or drain pan due to dirt and debris buildup over time. If you don’t regularly clean the overflow pan in your window unit, the dirt, dust, and other particles can get stuck in the drain and cause a blockage.

Unfortunately, this blockage can prevent the window AC from draining properly, causing water to leak out from the window unit instead of staying contained in the drain pan, where it belongs.

2. Frozen Evaporator Coil

Another common cause for window air conditioner leaks is freezing in the evaporator coil. If your window unit has a dirty air filter, the restricted airflow won’t allow the evaporator coil (which is cold) to release that cold air. In turn, it will freeze.

When it does indeed thaw, all of that ice will cause leakage from your unit.

3. Dirty Air Filters

As mentioned briefly in the previous point, air filters are designed to capture debris before they get inside your window AC unit. But when these filters become too dirty, they can block the window unit’s airflow and cause a multitude of problems, including water dripping outside. That’s why it’s important to regularly clean or replace the air filters in window units to keep them functioning properly.

4. Improper Installation

If your window AC unit was not installed properly, it could be at risk of leaking water outside. A window air conditioning unit should always be securely mounted so that the window provides adequate support for the entire weight of the window AC unit. If this isn’t done correctly, there is a chance that your window AC could leak water outside due to an improper installation job.

5. Low Refrigerant Levels

When your AC unit has low refrigerant levels, this can also cause your unit to leak. Refrigerant is a fluid that aids in the process of cooling the air in your window unit.

Low refrigerant levels can occur due to a refrigerant leak or simply due to the unit being old and not able to properly hold refrigerant.

6. Cracks & Rusting

Window air conditioners can also start to leak water if cracks form on their exterior due to age or excessive rusting. If you notice any cracks in your window AC unit, it’s important to get it fixed as soon as possible in order to prevent water from leaking out.

How To Fix Window Air Conditioner Leaks

If you do indeed find that your unit is leaking puddles, it’s best to find the cause and fix it as soon as possible. You can DIY if you believe you can handle it yourself, or you can seek professional help. Either way you chose, the following steps can be helpful.

  1. The first step you should take is to turn off your AC unit. This will prevent any further water damage from occurring.
  2. Next, you should clean up any mess that the leakage is causing, so that you don’t have further damage to worry about later.
  3. Then, identified one of the causes mentioned above for why your window air conditioner is dripping outside. If you can’t figure it out on your own, then it’s best to contact a professional HVAC technician who can accurately diagnose and repair window air conditioning leaks.
  4. If window air conditioner water leaks are found to be caused by a clogged drain or dirty air filter, you or the HVAC technician will clear out the blockage and replace the dirty filter with a new one.
  5. If freezing is causing leakage, then you or the technician will check to make sure there is adequate insulation around the window unit and repair any cracks that are present.
  6. If your window air conditioner is leaking due to improper installation or other more serious issues, such as a broken condensate pump (only for basement-level window units), oftentimes the professional HVAC contractor can diagnose and repair these problems too – quickly and efficiently.

Preventing Window Air Conditioner Leaks from the Beginning

Preventing Window Air Conditioner Leaks from the Beginning
Image Credit: weekand

Now that you know some of the most common causes for window air conditioner leaks and how to fix them, it’s important to also understand how you can prevent these leaks from starting in the first place. Here are a few pro tip pointers:

Install the Unit Correctly

The best way to prevent window AC unit leakage is by having it installed correctly. You should always hire a professional HVAC contractor who will ensure that the window air conditioning unit is securely mounted in place and sealed properly. That way, you won’t have to worry about window air conditioner water leaks or other problems in the future.

Regularly Clean the Unit

Another thing you can do is to regularly check and clean window AC unit, such as cleaning the fan blades and making sure the float switch is functional. These are some of the good things to check because if they aren’t working properly, window air conditioner water leaks can be more likely to occur.

Routinely Check for Damage

Lastly, regularly check your window AC unit for cracks or rusting, as these can lead to window AC unit leaks. Especially check for these issues if your AC unit is old, or if your home has recently been through a major storm, such as large hail or high winds. If you do find any damage, make sure to contact a professional HVAC contractor as soon as possible to determine if you need to repair or replace the unit.

When Should a Window Air Conditioner Be Replaced?

In some cases, window AC unit leakage can be so severe that the window air conditioning unit needs to be replaced. If your window AC unit is old and has developed a major leak or other serious problem, then a complete replacement may be the best option.

Before you purchase a new window AC unit, however, make sure to check the condensate drain line and ensure there’s no blockage or buildup of particles that could cause window air conditioner water leaks in the future. This is important as even with a brand-new window air conditioner, if the condensate line isn’t clear and clean, then window air conditioner water leaks can still occur.

It’s also important to make sure the window AC unit is installed correctly – that means securely mounted in place and sealed properly, as we have discussed before. Once everything is in order, you can rest assured knowing that window AC unit leakage won’t be a problem.


Overall, window air conditioning units are great for keeping your home cool during the hot summer months, but they need regular maintenance in order to keep them running properly. If you notice water leaking from your window AC unit outside, then it’s important to call in a professional HVAC repairman as soon as possible to diagnose and repair the window air conditioner leak. This will help prevent further water damage from window AC unit leaks and excess humidity levels in your home.

By following these tips, you can ensure that your window AC unit will keep your home cool without any issues or water leaking outside.

Do you have any other questions about your window air conditioner unit? Let us know in the comments below!

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