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A/C Leak: Potential Causes and What to Do

air conditioner leaking water inside

Have you been struggling with a leaky AC unit? Are you wondering how this could have happened and what you can do to fix it?

There are many causes that can contribute to an air conditioner leaking water inside the home.

So it's important to learn what the culprits are. And that's what we're here to help with. We want to arm you with the right info to help not only fix the issue, but also prevent it from happening again.

If that sounds interesting, then keep reading.

Because in this article, we are going to explain why leaky units happen and what you can do about them.

How Water Appears in Your AC Unit

The majority of present-day AC setups have indoor and outdoor units. An evaporator coil is used in the inside unit to cool the air as it passes through.

This is what creates a pleasant and enjoyable room temperature. Once the air heats up and begins blowing over the coil, condensation forms.

As the moisture spreads, it trickles onto a pan below that's connected to a line for condensation. And this line is then ushered out of your home to avoid any water leaking through the ceiling.

But no system is perfect.

And there will be times when leaks in AC units happen in your home. Here are a few reasons why this may occur.

Why AC Units Leak

You may be asking yourself: why is my AC leaking water? There can be many reasons, but one of them may be a jammed condensation line.

As time passes, continual usage can cause this line to get backed up with all types of debris. Anything from dirt, sludge, grime, and other kinds of filth could easily block the line.

When this happens, the water becomes trapped and can't flow to the outside where it's supposed to go.

This forces the condensation back up the line and into the unit, which then leads to water leakage through ceiling crevices.

How to Prevent Water Leakage

When it comes to preventing or fixing AC leaks, we have your back. It's best to take care of these things sooner rather than later, and a few preventive measures can go a long way in making that happen.

Here we have provided a few tips to assist you:

Replace Air Filter

Generally speaking, you should replace your air filter about every 30 days or so. When a dirty air filter is not replaced, it makes the whole unit work harder.

This can result in unnecessary damages and can even exhaust many of the important parts of the unit.

Furthermore, a dirty filter can also block the airflow that goes to the unit's evaporator coil. This blocked-off airflow can cause the coil to freeze.

Then when the coil dethaws in the warmer months, the extra water will cause your pan to overflow, resulting in leakage.

This could be one of the reasons why an AC unit leaks.

Thus, it's crucial to practice vigilance with your air filter. Be sure to change it every 30 days or two months, max.

Low Refrigerant in AC

When the amount of refrigerant runs low in your AC, the pressure inside becomes lowered as well. This will freeze your evaporator line and cause leakage.

We recommend staying observant of any temperature fluctuations. If the AC is not keeping your home cool, this could be the result of low refrigerant. Other indicators are strange hissing or popping noises.

The best solution is to be cognizant, catching a leak beforehand makes it easier and cheaper to repair.

Waiting for long periods of time before attending to it will result in having to pay a professional to fix or replace the unit entirely.

We suggest inspecting your AC unit often to avoid such issues. Our recommendation is at least once a year, at the beginning of each summer.

Other Causes of AC Unit Leaks

When it comes to air conditioner leaks, we know there are more than just a few issues at play. For this reason, we want you to understand all the potential problems that could occur.

Another cause could be an aged unit. Once your AC system has gained some experience, it could develop rust as well as an impaired drain pan.

AC systems 12 to 15 years old need to have their drain pan replaced. A new pan is sometimes all it takes for fixing AC leaks.

An additional culprit could be a damaged AC condensate pump. Water can't be pumped outside with a compromised pump, that's why we suggest you look at this as a potential source of your water leakage.

If this happens to be the case, it's important to fix it as soon as possible. If it's not serviced or replaced, it could cause significant damage to your home.

How to Fix a Leaky Air Conditioner System

There is no one size fits all for AC unit leaks. That's why it's crucial to understand what's causing your leak before taking any corrective action.

Because depending on what's actually causing the leak, different methods will have to be applied.

Here are some solutions for each one of the potential causes:

Solution for Blocked Condensate Line

Some of the most common leakages in AC units come from a blocked condensate line. When the line is not cleaned, accumulated blockage accrues. This causes a build-up as well as an eventual overspill of water.

The first step is to turn off the AC unit, then find the pan to check for water. Empty it out and give it a very rigorous clean. 

Second, find the drain line, then see how stopped up it is. Then take a wire brush (make sure it is long enough), and scrupulously clean out the line. Take out the goo, slime, and whatever else happens to be lodged in there.

If it's seriously jammed, there are specially designed pumps and vacuums that can be used to clear them out.

We suggest testing it to ensure it was thoroughly cleaned. This is done by pouring water down the line, and if it flows smoothly out to the other side, then it's a job well done.

And lastly, for preemptive purposes, we suggest focusing on HVAC preservation. We recommend pouring bleach in every 3 to 6 months to clear out the drain line.

This eliminates germs and stops bacteria from forming.

Solution for Damaged Pan

Found under your air conditioner's evaporator coils, the pan (or drain pan) catches condensation when it drips from the coils. The water then goes from the pan, through the drain line, right to the outdoors.

But if the pan is broken, the water leaks rather than flows to the outside.

The solution here is to cautiously and firmly seal the cracked or damaged pan.

Wash the pan, and once cleaned, look for and identify all the cracks that you can find. Use a water-resistant sealant to strengthen the once fragile blemishes, and then test the restored pan by pouring water on it.

Solution for Broken Drain Line

A disconnected drain line can also cause water leakage for your AC unit. The line can break due to poor fitting, shoddy repairs, or even regular wear and tear.

To repair this problem, get in touch with an HVAC expert who can come in and make the repairs.

Solution for Ruptured Condensate Pump

Having an AC unit in an obscure place, such as a basement, makes it harder for the water to run from the drain line. This is where having a condensate pump comes into play.

If the water in the condensate pump increases, the pump's switch turns on. This signals the pump to remove the water; draining it to the outside.

If the pump or the switch is broken, the water won't drain.

This is not an issue you can fix on your own. Call a technician or an expert to replace or fix the pump.

Solution for Build-Up of Condensation

Excessive build-up of condensation can cause AC water to leak in air-ducts, vents, the roof, etc. And this can be very costly, so it's crucial to prevent this from taking place before it's too late.

A good first step we suggest is to have your ductwork insulated. When this is done, the mild air can't get to the chilly ducts. But if the duct is already insulated, check for damages and fix them as quickly as you can.

Next, if the ductwork runs through your attic, it's a good idea to insulate that as well. If there are damages to your roof, contact a repairman to fix this so you can avoid any more damage from condensation.

Also, have a schedule for maintenance upkeep. This can prevent many condensation issues as well as save you a lot of money over time.

Solution for the Freezing of Evaporator Coils

Evaporator coils are an essential piece of the AC system. But they are also very vulnerable parts of the system.

All it takes is a refrigerant spill or clogged air supply for them to freeze. This then leads to increased moisture, which causes the pan to fill up and leak.

Our solution here is to look at the filters, ducts, vents, etc. If they're dirty and unwashed, then take the time to give them a good cleaning.

By doing so, the airflow will return back to normal. And furthermore, the freezing along with the leaking water will no longer be an issue.

Also, if the problem persists after these measures, then you may need to refill your refrigerant.

Solution for Mucky Air Filters

Air filters provide proper airflow. They catch pollutants and, as a result, purify the air when it flows into your home.

But over time, the air filters become grubby, stained, and dusty. This clogs them up and stops them from being effective at their job.

This will compromise the quality of the air in your home and can be another source of damage to your AC. 

One of our solutions is to first gather the leaking water. Once this is done, clean out the filters. Allow them time to dry out before placing them into the unit again.

We advise that you clean your air filters every couple of weeks, as well as restore them at least every 4 months.

Solution for Improper Installation

If you've put in a fresh unit recently, and it happens to be leaking, you may be thinking or asking yourself: is water leaking from air conditioner dangerous?

And the answer is: it can be if it's left untreated. And oftentimes, this leakage is due to improper installation.

For instance, seemingly innocuous things like the drain pipes along with the unit not installed proportionally can cause leaks. Likewise, when an AC unit is off and not leveled correctly, it can overturn water within the home.

Our solution, in this case, is to put the AC unit on a flush surface. If the surface is rutted, lumpy, or rough, use some kind of pad to even it out.

An AC unit for a window should be angled skyward from the forefront, so the water flows outside rather than leaking inside.

And lastly, when setting up a fresh AC unit--unless you're trained, educated, and certified--always make sure that an expert is getting it done.

Is Your Air Conditioner Leaking Water Inside?

A basic understanding of an AC unit is all that's needed to solve the problem of an air conditioner leaking water inside. And we hope this article has provided you with that understanding.

However, we know that sometimes a little extra help is required. So if you need additional information or would like help fixing a leaky AC unit in your home, be sure to give us a call.

We look forward to hearing from you!


3850 E. Baseline Road #115
Mesa, AZ 85206
Ph: 480-270-8000