Brown Sludge in Window Air Conditioner? (Causes & Solutions)

By - Ron Singh

Updated -

The state of your air conditioner guarantees the quality of the air you’re inhaling; this means that if your air conditioner is untidy, you’re likely inhaling unclean air.

For example, having brown Sludge down your window air conditioner pipes signifies that you need to clean your air conditioner. 

Also, apart from the air quality, the Sludge’s presence can affect how the air conditioner works.

Brown Sludge is a general term that describes different dirt particles clogged up to form a thick brownish substance in the pipes of the air conditioner. Not necessarily the pipes, but Sludge can form on any part of the air conditioner with enough humidity. It is because of the condensation in such areas that it becomes a breeding ground for germs.

Why Is There Sludge in My Window Air Conditioner?

Brown Sludge in Window Air Conditioner

The working principle of your air conditioner makes it possible to flush out water that forms from the condensation it gathers through narrow copper pipes. These pipes flush out the water and dirt sieved by the air conditioner. 

And since the pipes are narrow and constantly moist, it becomes the perfect place for mold, fungus, mildew, and other types of bacteria which make up the brown Sludge you see in these pipes.

Sludge is a product of the condensation that gathers within the air conditioner and other trapped dirt and grows within that part of the air conditioner.

In reality, not so many people make time to clean the pipes and other hidden areas of their window air conditioner, so as long as it works, it is good to go. 

At the same time, the air conditioner will still serve you; sooner than later, you’d have to expend more energy and resources to service it because of the dirt in it.

There are misconceptions about air conditioners causing certain illnesses like pneumonia; to be fair, you won’t blame anyone for believing this.

Because the moist pipes are breeding grounds for some disease-causing bacteria and viruses, this seems believable.

Many people believe that extreme cold from the air conditioner causes pneumonia.

 It is not medically cleared and therefore is unfounded; pneumonia is a viral disease that occurs when you contact the virus and thrives in moist areas.

Dirt in the drain line of your air conditioner can breed bacteria and other viruses, which cause these illnesses believed to be caused by the air conditioner itself. 

What Are the Black Spots on My Window Air Conditioner?

The black spots on your window air conditioner are likely to mold spores if you’re sure they aren’t dust particles or other forms of dirt.

Mold spores grow in cool and dark areas, and a window air conditioner fits perfectly into this description.

 The dark corners around your mounted air conditioner are usually more excellent than the exposed areas of the air conditioner.

Coupled with the condensation in some parts of the air conditioner, you’ll likely have to deal with mold spores from time to time.

Generally, mold spores grow in wet or cool areas, for instance, on wet clothes, shoes, or walls with inadequate air or heat.

You may not notice it at first because mold spores are tiny spots, but once they aggregate into larger sizes, they become more visible and look like black spots on the areas they appear.

 So if you’ve noticed black spots on your air conditioner, what you’re seeing are aggregated mold spores that have grown over time.

Many modern homes have window air conditioners mounted in open spaces with enough aeration and heat to dry up any moisture around those areas.

It is contrary to how home decors formerly mounted air conditioners in tight and dark corners, which promoted the growth of mold and fungi on the air conditioner and walls. 

So if you’re wondering why people no longer keep their air conditioners hidden, it is not just about aesthetics but also to prevent the appearance of those black spots which turn out to be mold spores.

Interestingly, molds aren’t the only type of growth that can be found in the air conditioner, there are other microbes that can grow in parts of your AC and be a threat to your health.

Some of them and how to prevent their growth are listed below:

FungusReplace the filters regularly
BacteriaFrequently clean the air ducts or any channel through which air gets into the air conditioner.
VirusesClean and unclog the drain lines as they form a channel through which these microbes come in.

How Do I Remove Sludge From an Air Conditioner?

Fortunately, just like regular dirt in other home devices, having Sludge in your air conditioner is not permanent; with some maintenance, you’ll successfully clear your air conditioner.

In just very few simple steps, you can take out the Sludge from the air conditioner pipes and enjoy healthy air.

Here are the steps to remove Sludge from your air conditioner:

#1. Step 1– Turn Off Your Air Conditioner

Turning off the electronics you want to clean is fundamental for all electronics repairs.

No matter how simple or complex the device is, disconnect it from the power supply before starting any form of cleaning on it.

You may wish to switch it off and go on with the cleaning, but to be on the safer side, unplug it from the socket in case of any current leakages.

#2. Step 2– Locate The Drain Line On The Air Conditioner

The drain line is the external pipe that drains the air conditioner’s condensation. It is usually connected with the air conditioner’s external unit to prevent the water from pouring back into the house.

The drain line is where the Sludge and all other blockages are because it is the wet part of the air conditioner.

#3. Step 3– Locate The Access Point of the Drain Line

There’s an access point linking the drain line and the air conditioner, usually in a T-shaped vent with a removable cap.

Open the cap to gain access to the drain line. Other drain lines can be unscrewed from the air conditioner using a spanner.

#4. Step 4– Use Vinegar to Kill The Bacteria

Pour a small quantity of vinegar into the drain line through the vent and allow it for 30 mins.

Vinegar is a common household ingredient that fits into many recipes, but it is specifically known to be a suitable cleaning agent.

It kills bacteria and unclogs clogged spaces, and as little as ¼ teacup should effectively clean the drain line.

#5. Step 5– Flush With Water

Use clean water to flush the sludges as often as possible until the entire pipe is clean.

Observe the flow of water to know when the pipe is clear; if the flow is slow, it’s likely that some debris is left in the line and needs more flushing.

Considering how easy it is to clean up the drain lines of window air conditioners, it is a wonder why many people rarely pay attention to it.

But as mentioned, ignorance of the dangers of having Sludge on the air conditioner and the fact that it will still work even with a blocked drain line is why most do not pay attention to cleaning their air conditioners. 

However, it would be best to regularly clean the air conditioner once you realize that having Sludge in it is detrimental to your health and can also decrease its effectiveness.

Can Sludge/Dirt On My Window Air Conditioner Make Me Sick?

Yes, having Sludge on your window air conditioner can make you sick. The state of your air conditioner guarantees how healthy the air you’re inhaling is; inhaling unclean air will affect your health.

As earlier explained, some disease-causing viruses and bacteria thrive in moist areas, and if these viruses find themselves in your system, they will make you sick.

One common illness inhaling unclean air causes is pneumonia. Bacteria, viruses, influenza, and fungi affect the respiratory system.

One of such Respiratory Syncytial Viruses(RSV) that causes pneumonia is Streptococcus Pneumoniae. 

It is why many people believe air conditioners cause respiratory infection, while in the real sense, the presence of bacteria in the pipes of the air conditioner as a result of Sludge makes one sick.

If you realize that you become sick after exposure to the air conditioner, you may inhale unclean air with some bacteria.

And the only way to prevent it is by cleaning the drain line on your air conditioner alongside the vents on the external unit with the stated steps. 

You may also like to check out the air conditioner area because some areas are more likely to attract bacteria and other disease-causing organisms than others.

For example, if the external unit of your air conditioner is in a moist and water-dense area, the chances of fungi growing in the drain lines are higher.

Final Thoughts

Many people do not know the dangers of having Sludge in their window air conditioners because people hardly pay attention to little details like these.

Thankfully, cleaning up the air conditioner does not require you to have technical knowledge. Therefore you don’t have to hire an expert to remove Sludge from your air conditioner.

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