Window Air Conditioner Leaking Water Outside? (We Have A Fix)

Ryan Womeldorf
by Ryan Womeldorf
Window air conditioner units are a fixture of old and modern homes alike, but they aren’t without their problems. It is common for window AC units to leak water outside, and that is generally due to a broken or damaged condensate pan. Whether it be frozen coils, a broken condensate pan, or a lack of refrigerant, let’s take a look at what you can do when your window air conditioner leaks water outside.

The air conditioning of our home can play an integral role in daily life. Especially in warmer climates or during the hotter months of the year, air conditioning that is working properly can make life a lot more comfortable. Perhaps you have begun noticing that your air conditioner is leaking water. So, what do you do? How do you fix this?

A window air conditioner can leak water when the air filters are dirty and when the condensate pan is damaged or broken. Clogged drain pipes also cause a window air conditioner to leak water outside. Window AC units also leak water when they run out of refrigerant and the evaporator coils freeze.

This guide will help walk you through the reasons your air conditioner may be leaking water outside. That way, you can fix the issue as soon as you find it to get your air conditioner back into tip-top shape.

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Reasons Your Air Conditioner May Be Leaking Water Outside

There are six common reasons your air conditioner may be leaking water outside. In order to fix the problem, you’ll have to first find and diagnose the issue. By following through the list below, you can figure out exactly what is wrong so that you can fix the problem before it becomes something more major.

Dirty Air Filters

When the air conditioning air filter gets to be dirty, that can lead to partial blockage or even complete clogging in the filter itself. This makes it far more likely that the evaporator coils of the air conditioner will freeze up.

When the air conditioner’s evaporator coils freeze up, this can cause water to start to overspill, coming from the drain pan. Keeping a clean air filter can be one way to ensure that excess moisture does not come from your air conditioning unit, though it could be a number of other issues that are the problem.

Drain-Pipe Blockage

What you may not have realized is that the water in the air conditioning unit actually travels to its drain pan. It does this using a fairly complex system made up of drain pipes. Whenever there is blockage in the drain pipes, that can cause water to leak out of the air conditioner unit.

Blocks can be simply to clear out but there is also a chance that they can be seriously clogged and cause damage to those drain pipes. If the pipes become damaged or too clogged to repair, you will need to replace them or have them replaced by a professional service.

Condensate Pan Is Broken

The age of your air conditioning unit can play a factor, too. If you have an older unit, the condensate pan can actually become rusted or even split or crack given enough time. When this is the case, the water will leak out from the air conditioner.

If you have an older unit, keep an eye on the condensate pan from time to time. Replacing it every few years can be a good way to extend the life of your unit and ensure that there are no leaks on the exterior of the air conditioner unit.

Improper Installation

Just like anything else, an air conditioning unit can function improperly if it hasn’t been installed correctly. If you have a new air conditioner and notice that is leaking quite a bit of water, this is likely because it wasn’t installed correctly.

Any improper sizing or a drainage pan that is installed incorrectly can lead to that water leaking from the exterior of the air conditioner. If you don’t feel comfortable doing it yourself, calling in a professional should result in the correct changes being implemented and the leaking issue should dissipate in short order.

Low Levels Of Refrigerant

When the levels of refrigerant are low in your air conditioning unit, the pressure on the system will also lower. When this happens, the evaporator coils can actually ice up. When the coils freeze over, the drain pan can then overflow and wind up leaking water.

Keep an eye on coolant levels when you can. Some newer models will even display coolant levels, making it easy to know when they are low and need to be refilled. Be careful to not let the evaporator coils freeze as they can become damaged and need replacing.

Colder Temperatures

When the air conditioning season (summer) is at an end, the air conditioner can actually start to leak if it’s too cold outside. If the air conditioning unit is attempting to cool down the home but exterior temperatures are at or under 60 degrees, the coils can freeze up. And when the coils freeze up, the unit will leak water.

When the temperatures start to come down at the end of the summer, keeping the windows open can be a great way to keep the interior of the home a bit cooler. Not only that, it can save on costs incurred from using the air conditioner unit all the time.

Fixing A Window Unit

Any issues with centralized air should go to a professional. There are too many components and things that can go wrong to leave it in the hands of an untrained professional. Having said that, many people will find dripping in their window air conditioning units and not know what to do.

The first thing to ask yourself is how long the unit has been dripping. Some issues can be persistent while others seemingly spring up overnight. Knowing how long the situation has been occurring can give you the opportunity to eliminate some of the potential causes.

Make sure that you wipe away any water that drips onto hardwood or any other kind of bare flooring. If this is something that has been allowed to persist or hasn’t been noticed for some time, the damage may already be done. The dripping water can be especially damaging on carpets and need to be addressed in short order to prevent the growth and spread of mold and mildew.

Checking The Drain Hole

The first thing you should do is check out the drain hole. One of the most common reasons that window air conditioning units begin to leak is due to that small drain hole at the back of the unit. When it becomes clogged, there is no other place for the water to go and it will start to leak out of the unit.

Depending on the temperature outside and how long it has been dripping, it can even start to drip into the home. Keeping an eye on your air conditioning unit is always a good idea because leaks or dripping left unchecked can do far more damage than you realize.

Check to see if there is a noticeable clog. Units that don’t have a hole may have a drain plug or a slinger fan. Take the plug out and let any water that is inside to drain out. If you have a sling-ring, under no circumstances should you drill a new hole. Read the manual if you have any doubts and it will tell you what to not do in regards to your air conditioning unit.

In most cases, there will be mud, twigs, or debris in that hole. Simply remove it and clean the hole and you should notice that the dripping or leaking will stop after the hole has been plugged up again.

Consult The Manual When Installing

Another common reason that window air conditioning units leak or drip is due to improper installation. It is only common to buy a unit yourself and then install it. And while that is fine and well, far too many amateur handymen ignore the directions and install how they think it will work.

Follow the directions and you should have a proper installation. If you didn’t follow the directions the first time around, turn the unit off, remove it, and then follow the instructions for the installation. More often than not, this will alleviate the issue and remove any excess water that may have been collecting and leaking out of the unit.

When To Call A Professional

Of course, there are going to be times when you cannot fix an appliance and may need to seek some professional help regarding the matter. Before you toss your air conditioner out, you should have someone look at it to tell you if it’s a fixable problem or if you need to replace the unit entirely.

However, if the repair cost is going to be more than the unit itself, or close to the amount it would cost you to buy a new unit, then you might as well toss it and get a new one while you’re ahead.

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Wrapping It Up

There are numerous reasons that your air conditioner may be leaking water on the outside. By walking through the potential causes, you will end up finding the issue that needs fixing. However, if you can’t find this on your own, it may be worthwhile to hire a professional to take a look at it to help you decide if it’s worth fixing, or if you should just replace the whole thing.

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Ryan Womeldorf
Ryan Womeldorf

Ryan Womeldorf has more than a decade of experience writing. He loves to blog about construction, plumbing, and other home topics. Ryan also loves hockey and a lifelong Buffalo sports fan.

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