Is Your AC Leaking Water? (7 Possible Causes & Fixes)


AC Leaking Water

The air conditioner is without a doubt one of the most important aspects of the home. When the weather starts to get hot, it can mean the difference between enjoying the summer comfortably or sweating it out in your own home. Central air can be costly, so having a window air conditioning unit can be infinitely valuable.

From time to time, you may notice that your air conditioner is leaking. The leaking can be the result of a number of components. It could be due to a broken condensate pump, a clogged drain line, a damaged drain pan, and more. It is important to troubleshoot the issue to locate the problem. Leaking water can cause damage to other areas of the home that require further repair.

Why is Water Forming in the Air Conditioner?

Inside each air conditioner is an evaporator coil. Those coils are what cool the warm air that gets blown over top of it. When that happens, condensation will form on the coil. When you think of condensation, think about the water that forms on the outside of a cold glass of water during a particularly hot day.

That moisture then drips down into a drain pan meant to catch condensation. It then goes into the air conditioner’s condensate drain line. The condensate drain line leads to the outside of the home so that the water can drain away safely.

There are a few likely culprits for water leaking out of the air conditioner and into your home. Start by troubleshooting these issues and you can likely implement a quick, easy fix.

1. Condensate Drain Line is Clogged

Perhaps the most common reason that your air conditioning unit would leak water is due to a clogged condensate drain line. When the drain line gets clogged with dirt, dust, mold, or sludge, the water has no place to drain.

With no place to drain, the water backs up into the home. When that happens, start by checking for a clog. You can use a number of different methods for unclogging the issue. A wet/dry vac is probably the best method as it can be used to clean up any mess or leaking happening in the area.

Start here first. It is not only the most likely cause, but one of the simplest to resolve as well. When you are confident that the condensate drain line is not the issue, you can move on to other troubleshooting areas.

How to Clean or Unblock a Condensate Drain Line

It goes without saying that you can always call in a professional to implement cleaning, repairs, and replacements. But if you want to try it yourself, cleaning or unclogging the condensate drain line is a fairly easy endeavor.

  1. Locate the PVC. Start by locating the PVC pipe that is near the drain pan. There should be a piece of pipe that sticks up at a 90-degree angle and should have a little cap on top.
  2. Add vinegar. Take the cap off of the PVC pipe by unscrewing it gently. Keep the cap stored safely nearby and then pour about six ounces of vinegar into the drain line. It is a good idea to do this every couple of months as the vinegar kills fungi and algae that can develop in the condensate line. If it is still clogged, you can use a wet-dry vac or you may have to call in a professional.
  3. Wet-dry vac. If you have a wet-dry vac, you can start by locating the condensate drain. It is located near the condenser unit. Connect the attachment on your wet-dry vac, and then turn on the vacuum. This should work to suck out any loose debris or buildup that lives in the condensate drain line.

2. Broken Condensate Pump

On the off chance that your air conditioning unit and furnace are installed in the same room, there will likely be a condensate pump, too. The condensate pump is what pumps any water outdoors and away from your home.

When the pump breaks or stops working, water doesn’t get pumped outside anymore. It will then start to pool up, causing damage in the immediate area. Pumps can be replaced or repaired, but it might be best to have a qualified professional do the job.

3. Damaged Drain Pan

There could also be issues with the drain pan. While the drain pan is not the most complicated piece of equipment, it is vital to preventing leaking. The drain pan catches any leaking or water that falls into it from the condenser coils.

When the drain is clogged up, rusted, or even cracked, water will either fall right through it or roll over the top edges. Since the pan is small, it is not repairable. You will need to replace the pan entirely to keep water from leaking out into your home.

4. Dirty Air Filter

Believe it or not, a dirty air filter can play havoc on both your furnace and any air conditioner units. Its primary role is to filter out pollutants – dirt, dust, pollen, etc. – in the air before it gets into your air conditioner unit.

When the air filter is blocked, airflow can’t properly reach the evaporator coil. And when that happens, the evaporator coil can get too cold and even freeze over. The dripping is excess water that eventually overwhelms the drain pan.

How to Fix it. After the condensate line, the air filter is the next place to look. If it is dirty, change it out immediately. A good rule of thumb is to replace the air filter every 1-3 months depending on what season it is. A dirty or clogged air filter can be the culprit in many instances.

5. Low Refrigerant

When refrigerant is low, it can have the same kind of impact that a dirty air filter does. It basically lowers the pressure within the air conditioning system. That leads to the evaporator coil freezing over. When the coil then melts, water will drip down into the drain pan, overflowing it at some point.

There are a couple of signs that can help you recognize when your air conditioner is low on refrigerant. Those two signs are:

  1. Hissing or bubbling. If you notice hissing or bubbling emanating from your air conditioning unit, the most likely reason is low refrigerant. There are other potential causes, but this is the place to start.
  2. Isn’t cooling. Should you start to notice that your air conditioner isn’t cooling very well, low refrigerant could be the main cause. Keep in mind that a lack of cooling could be due to a more serious issue, but low refrigerant is a good place to start.

How to Fix it

Adding refrigerant should be done by a professional. It is also important to note that, generally, the air conditioner unit shouldn’t need a refill. It is only when there is an issue with the air conditioning unit that refrigerant could be low.

There is also the possibility that you are experiencing a refrigerant leak. When that happens, any refrigerant that goes into the air conditioner will eventually leak out. Depending on how severe the leak is, repairs may be possible. When they are of a more severe nature, there is a risk that the entire air conditioning unit will need to be replaced.

6. Frozen Evaporator Coils

After the condensate line and the air filter – the two most likely causes – the evaporator coils should be one of the next spots to look. As mentioned previously, a dirty air filter can prevent air from passing over the evaporator coils.

When there isn’t proper airflow, the coil can freeze up. Refrigerant flows through those coils and needs proper airflow in order to absorb the heat. Without that airflow, ice will form over the coils and eventually drip water.

How to fix it. Thankfully, frozen coils generally mean that there is a buildup or blockage of dirt somewhere. Start by looking over the various components, cleaning them as you go. Replace the air filter.

Should you notice that the evaporator coil is frozen, start by turning off the air conditioning unit entirely. Don’t turn it back on until you have thoroughly cleaned all the components or had a professional replace it entirely.

7. Improper Installation

With window unit air conditioners, there may not actually be an issue with the unit itself. It could be that the unit has been installed properly and doesn’t seal outside moisture off. When this happens, it is easy for moisture to collect around and beneath the air conditioning unit.

Check the area where the air conditioner is installed. Look for any noticeable gaps around the unit itself. Even if you can’t find any gaps, it may be worth it to pop the unit out and re-install it to ensure that the problem is not installation.

How to Tell if Your Air Conditioner is Leaking Water

While it may seem obvious when your air conditioner is leaking, that isn’t always the case. Yes, water can be seen to indicate a problem, but there are other instances where you may have a leak and not see it. Here are a few ways to tell if you have a water leak in your air conditioning unit.

  1. Standing water. This is the easiest way to tell that you have a leak. When there is standing water, you can generally trace it back to a leak or drip somewhere in the air conditioning unit. Depending on the severity of the leak, the standing water could be a small puddle or something much larger.
  2. Smell of mold. Sometimes, though, that leak isn’t quite so evident. If you don’t see a leak but think there still may be one, there is a chance that you notice a moldy smell in the home. At the very least, you would smell mold in the room where the air conditioning unit is located.
  3. Condensate pan is full. Should you suspect a leak but don’t notice puddling water anywhere, you can always check the condensate pan. This pan is not something that you will be required to empty regularly if it is working properly. If it is full, that is an indication of a problem elsewhere, likely with the condenser coil.
  4. Water damage. When leaks are allowed to persist for long periods of time without being repaired, the consequences can escalate. You may notice water damage in the form of water spots or rotting either on the unit itself or on nearby walls or flooring.

Related Questions

Should I Keep My Air Conditioner Fan at “ON” or “AUTO”?

There can be some confusion as to which option is better for your air conditioner unit. But there are distinct pros and cons to these features to be aware of.

Pros for Auto. Leaving the air conditioner fan on “auto” is the most energy-efficient choice. This means that the fan doesn’t run continuously, only when the system is on. Auto also allows for moisture to drip outside of the home more effectively. Finally, if the setting is on “auto”, then the filter isn’t working as hard as often.

Cons for Auto. Cool air may not be distributed as evenly. Also, when the air hits a certain temperature, the fan will turn off instead of continuously blowing cold air. This leads to the blower motor fan wearing down sooner rather than later.

Pros for ON. When the fan keeps going, air continues to circulate. That reduces the chance for random pockets of uneven air in your home. There will also be less stress on the fan attributed to frequent starts and stops.

Cons for ON. With the fan running nonstop, your cooling costs could go up. Check the use levels of your air conditioner; some aren’t rated to be used continuously. In the winter, there might be cooler air coming out of the vents, making it difficult to keep your home warm. The filter will also need to be replaced more often since air is constantly being blown through it. Finally, the ducts can wind up filling with warm air in the summer, blowing hot air inside.

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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