Disclaimer: As an Amazon Associate I earn from qualifying purchases. It may also contain other affiliate links. Read our affiliate disclosure.

ac condensate line sweating

Why Is My AC Condensate Line Sweating? – What To Do

Are you wondering why your air conditioner condensate line is sweating? It’s a pain. But don’t alarmed, you are not alone. 

Many homeowners have come across the same issue; the good news is that it is easy to fix. In most cases, all you need to do is add insulation to the drain line. 

In this post, I will walk you through the reason why an AC condensate line is sweating, plus the solutions. 

So, without further ado. Let’s jump right in!

Why is my AC condensate line sweating?

The condensate line is also known as the drain line, which is the PVC pipe that is responsible for draining the condensate produced by your AC. 

When the warm air in the room passes through the evaporator coil in the indoor unit, the moisture will be removed and collected in the drip pan. The water will then get into the drain line through the drain hole in the drip pan. 

See also: how much water should be in an ac drip pan?

Since the evaporator coil is cold, the condensate will also have a low temperature. Accordingly, the condensate line will have a cold surface.

As you know, the air on summer days is hot and humid, especially in the attic. When the air in your house comes in contact with the cold surface of the condensate line, its temperature will decrease.

When the air temperature goes below the dew point, the water vapor will turn to liquid, causing condensation. That’s why you will see the AC condensate line is sweating.

Is it normal for the AC condensate line to sweat?

While it is normal to see condensation on the condensate line, it is not recommended to leave it unattended. 

Damages to floors and furniture

This is because excessive sweating means that the water droplets can drip on the floor or cabinet. For example, your pvc pipe may drain into the traps under your sink and the condensate water on the pipe will drip into the cabinet.

If it continues to happen, your house will run the risk of water damage. Or you will need to put a bucket under the pipe to catch the condensate.

Growth of mold and mildew

Beyond that, the sweating condensate pipe can increase the humidity level of the surrounding air, promoting the growth of mold and mildew. 

If you are one of those who are prone to allergies, this is definitely something you want to avoid.

How to know if your AC condensate line is sweating, not leaking?

Before you start to deal with the sweating pipe, you should make sure the excess water is not caused by the leak since it will need different fixes.

Most leaks occur at some places near fittings, and you can often see black or green stains around them. It will leak water continuously even if the climate is not so humid.

If you are not sure about it, just make a call to a professional.

How to stop your AC condensate line from sweating?

Now that you have understood why your condensate line is sweating and its side effects, let’s explore how to fix it.

Add insulation

add insulation to ac condensate line

Adding insulation to your AC condensate line is the ultimate solution if you live in high-humidity areas. In this way, the humidity outside will not affect the pipe. As a result, it will not sweat.

Don’t worry, it is light on the pocket and easy to implement. You can check out the video from Expert Express plumbing heating and air conditioning I list below.

Run a dehumidifier 

Alternatively, you can run a dehumidifier with your air conditioner at the same time.  The indoor humidity level will decrease further, reducing the chance of condensation. If you have a portable dehumidifier, just place it near the pipe.

However, this solution will become useless if the sweating pipe is located outside.


If you live in humid areas or have an air conditioning system installed in the attic, chances are the condensate line will sweat at some point. Luckily, you can fix it easily by adding insulation or running a dehumidifier.

You should also take a look at the refrigerant line. If it is also sweating, you can find the solutions here.

Avatar photo

Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested more than 150 products in person, including humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

Leave a Comment

Table Of Content