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Why is My Air Conditioner Leaking Water?

As HVAC pros, we experience customer calls due to a variety of situations. In addition to strange air conditioning noises, we also receive calls when an AC system is leaking water inside the home.

There are different types of air conditioners, degrees of “service mileage” on these units, and therefore various potential causes behind a water leak. The best specific advice and troubleshooting we can provide comes with personal knowledge of your ac system. 

This article discusses the most common reasons you might experience a leaking AC in your home for some basic DIY troubleshooting. We hope it reveals a quick and easy fix, but as always, please give us a call for more in-depth help. 

Diamond Blue is a top-rated air conditioning repair company based in Carrollton, serving residential and commercial customers all across DFW.

Now let’s get into it.

5 Reasons Why Your AC Unit is Leaking Water and How to Fix It

First off, let’s establish that it’s not normal to have your air conditioner leaking water. If this is happening to you, be sure to turn off your system to avoid further water damage to your home.

Every AC unit produces moisture as a normal byproduct of the cooling process. Water forms as condensation on the evaporator coil as the coil cools the warm air that blows over it.

A great way to imagine this heat transfer process that results in condensation is this. When you place a glass of ice water on the counter, condensation begins to form on the outside of the glass. This makes it wet to the touch, and the reason your mother always told you to use a coaster.

In a similar fashion, excess moisture should leave your ac unit and drain out of your home through something called a condensate drain line.  If the drain line is clogged, the water should drip into a drain pan or the system should turn off because it triggers a safety float switch.

The most common reason your air conditioner is leaking water inside is often related to an issue with the drain pan or condensate line.

With this background on how your air conditioning system both produces and manages water, let’s now discuss these specific areas of concern to see why it might be leaking.

1. Condensate Drain Pan is Damaged

Your condensate drain pain is located inside of your air conditioner’s air handler beneath or beside the coil, depending on its location and a vertical vs horizontal installation. The moisture drips into this pan aided by gravity and will make its way outside via the drain pipe. But if the pan is damaged this process will be interrupted.

Most drain pans are metal and can become corroded over time. If your air conditioning unit is more than 10 years old, it’s possible that rust has eaten holes through the condensate pan. In this instance, you’ll need to replace the pan because it will result in water leakage.

In some instances, a drain pan can actually be made of hard plastic. Even a small crack can result in the ac leaking water.

Replacing the drain pan is a fairly easy air conditioning repair for a qualified technician. However, it can be challenging for the average homeowner due to access and proper replacement in relation to the coil.

Also, it’s a good idea to maintain your ac system each season to prevent leaking water inside due to a faulty drain pan.

2. Condensate Pan is Full

Any drain pan can fill up with debris such as biological elements (mold/mildew), dust, insulation, and even bugs or critters regardless of its type or age. Many DFW homes have their air handler (often referred to as the furnace) in the attic. This not only allows for the occasional mouse or insect nest to find its way into the unit but also poses a greater risk of increased damage should water leak down through the ceiling.

Even a “full” condensate drain pan should not leak because it should be equipped with a safety feature called a float switch. This switch is designed to power off the system should water exceed a certain depth. This mechanism keeps water from spilling over if it’s not draining properly. However, if the switch isn’t working properly the pan can overflow and leak water.

This problem is two-fold. Any debris should be removed from your drain pan, but if your air conditioner was leaking water and it didn’t power off, you may also need to have the float switch replaced. 

3. Clogged Condensate Drain Line

Your AC’s condensate drain line is attached to your pan and moves water from the pan to the outside of your home. You can see how a clogged drain pipe is closely related to the previous issue of a poorly functioning pan.

This drain line is often a 3/4″ PVC pipe, but in older air conditioners it might also be a hose. Any pipe or hose can become clogged with mold, mildew, or other debris. These clogs are one of the most common causes of an air conditioner leaking water.

Some clogs are obvious and occur near the exit of the drain pan itself. Your line might even feature a cleanout for easy inspection. If it does, it’s a good idea to regularly pour a small amount of vinegar down the line to combat mildew growth during seasonal operation. However, chances are that if you’re reading this troubleshooting guide you’re past the point of maintenance.

If the condensate drain is clogged somewhere inside the line, you’ll likely need professional help from Diamond Blue to locate and clear it. Depending on the severity, our professionals may use a wet vac, plumbing snake, or special cleaner to break up the clog.

Special Note: Your system might feature a condensate pump if your system is located in a position where gravity doesn’t fully aid the removal of water. A pan problem or clogged drain line might initially appear as false positives, but instead, your condensate pump could be faulty. We can help identify if this equipment is in play for you or not.

4. Air Filter Needs to be Replaced

If your air filter is too dirty it will restrict or block airflow. Not only can this result in a frozen evaporator coil, but excess water production can lead to an AC leak. This can happen slowly, or it can happen quickly as the frost melts and it overwhelms the condensate pan.

A dirty air filter is never good for your system, even if it doesn’t lead to an AC unit leaking water. We recommend changing flat filters every month and pleated filters every three months to prevent this from happening to you.

If you can’t remember the last time you changed your filter, turn off your air conditioner at the thermostat. Then remove the filter and hold it up to the light. If you can’t see light through it, replace it.

When in doubt, change it out. This will help your system efficiently deliver cool air and prolong the life of your entire system. It will also help maintain better indoor air quality.

5. Air Conditioner is Low or Leaking Refrigerant

Your air conditioner relies on refrigerant to facilitate the transfer of heat and keep your home cool. When your air conditioner doesn’t have enough refrigerant, the system will work harder by running longer and this can wear down vital components.

We are listing this as a separate “cause” due to being such a common reason behind air conditioning repair calls that we receive. Technically speaking, it is another reason alongside dirty air filters that a frozen evaporator coil can develop. As stated, this excess moisture can overflow the condensate pan when it melts, resulting in a water leak.

There are a couple of signs that your air conditioner is low on refrigerant. The most common is that your AC system runs but it isn’t as cold as it used to be. If you notice comfort issues or warm air from your vents during the summer, you should have your levels checked.

For the trained eye and ear, bubbles can be visible and you might notice actual noises near the unit. These result from the escaping liquified gas and are a clear sign of a refrigerant leak. However, not all leaks are visible or audible. In fact, most are not.

Depending on the type of refrigerant your air conditioner uses, we are often able to repair your unit. There are cases we may recommend air conditioning replacement over repair, especially if your air conditioner runs on R-22 or Freon. 

This is due to the fact R-22 is no longer being made because of its damaging effects on the ozone layer.

Restoring your system’s refrigerant levels will clear up the problem of leaking water when the coil can function normally again.

How to Fix a Leaking Air Conditioner and Prevent It from Happening Again

We hope this list helped you identify some of the most common causes behind air conditioner leaks in the DFW area. Some can be easy fixes for the handy homeowner, but in many instances, you’ll need an HVAC professional like Diamond Blue to fix your leaking air conditioner.

Did you know that lack of routine maintenance is one of the top causes of air conditioning problems? Having your systems serviced at least once a year before the cooling season begins may help you avoid problems later in the summer.

We know you’re busy and it’s difficult to stay on top of air conditioning maintenance. With enrollment in our Diamond 360 Protection Plan, you’ll get a 22-point cooling tune-up in the Spring and a heating tune-up in the Fall, repair discounts, and priority service!

Too late for maintenance?

Whatever problems you’re experiencing with your air conditioner leaking water inside or even outside, our professionals are here to help.

We’re the heating and cooling company that treats customers like family, so give us a call at 469-200-3100 to schedule your appointment today.

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