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How To Clean Your Central Air Conditioner Drain Tube

Attic heating and air conditioning unit inspection

When it comes to summertime, air conditioning is our best friend. It’s our morning comfort, our workday solace and our hot summer night relief. We take it for granted...until something goes wrong and we’re left to fend for ourselves in 90-degree weather.

A common culprit of air conditioning malfunction? A clogged drain line.

Clogged air conditioner drain lines can lead to increased humidity levels, unwanted mold growth and musty odors. Those conditions mixed with summer heat aren’t exactly ideal. To help you maintain your unit all season long, we’ve identified exactly what you need to know about your air conditioner drain line: what it is, why it clogs and how to clean it.

Wait, what’s an air conditioner drain tube?

Any home that has a central air conditioner unit installed has a condensate drain line (or tube). Air conditioning units produce one natural by-product: water. When the warmer air from your home meets the colder surface of the evaporator coil, condensation occurs.

The water from your AC unit runs down the sides of the coil and collects inside the condensate pan, eventually reaching the condensate drain. It then flows off to the drain method your installer chose during installation.

There can be a variety of drain setups depending on the size, setup and location of your central AC system, so you will need to locate the drain on your system. If you can’t determine where your drain line is, it’s best to call a trusted HVAC professional.

Understanding your AC drain line: Sometimes it clogs.

The condensation formed in your AC unit is continuously traveling through humid drain piping -- a condition that algae and mold love to grow in. This algae growth will cause clogs. The more you work your unit, and the more humid your environment, the higher your chances are of extreme algae buildup.

Here’s how to tell if you have an air conditioner drain line clog:

You see flooding. If there’s water flooding around the air handler unit and dripping into the secondary pan, there’s a good chance it’s due to a clogged condensate drain line. This isn’t the only reason your unit is flooding, though. You may have cracked drain pans, frozen coils or even improper installation. If you suspect your drain line is clogged, call the experts for a professional inspection.

The unit won’t run. If your unit won’t cool because the drain line is clogged, it’s going to trigger the water safety switch. This switch prevents your home from being flooded when the drain clogs. To see if your unit triggered the safety, check the switch.

If the drain line becomes clogged, there’s no place for the excess water to go. This leaves your home opened to increased humidity, water damage and musty odors.

air conditioner maintenance

How to clean an air conditioner drain line

Regular care and maintenance of your air conditioning unit are essential to keep it operating at peak capacity. Drain tubes should be cleaned at least once a year to keep it free of algae and clogs. Here’s how you can perform air conditioner maintenance on your drain line:

  • Push clogs out with a vacuum. If you notice a clog starting to form, you may be able to remove it with a vacuum. First, remove the paper filter on the drain line. Then, try attaching a wet/dry vacuum to your outside drain line and use it to suck the clog out. Since it’s a lot easier to clean a line that isn’t fully clogged, this method works well to keep your line clear throughout the year.  
  • Break up the clog with a water hose. If you can locate a drain line end, you may be able to break up a clog using a garden hose. Using a hose nozzle, slowly apply water pressure into the drain pipe with small short bursts. Once it’s broken up, pour some hot water down the drain at the air handler to push the clog out. 
  • Try algae tabs. Algae tabs, which are small tabs used to prevent growth in your AC line, can be used in your drain pain once or twice a year to contain algae growth. While algae tabs aren’t known to entirely prevent formation, they may minimize growth.

Want more detailed instructions? We produced a DIY video showing you how to clean your air conditioning drain tube. View the video here.

The Secret Guide for Super Moms #2 Checking Your Air Conditioner John C. Flood

Stay cool all summer long

Simple maintenance tips can extend the longevity of your air conditioning unit, keeping your home cool all season long. Contact the Virginia HVAC specialists at John C. Flood if your AC unit is in need of an inspection, repair, or replacement. Call us at (703) 783-0247 or schedule AC service online.