How To Unclog An AC Drain Line

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Updated May 18, 2023

Regular maintenance is required for even the best air conditioners. There are a lot of components to consider, and today we’ll show you how to unclog an air conditioner drain pipe. For a quick rundown: Turn off the AC to be safe. Take off the cap or plug from the opening. Look inside for anything blocking the line. You can use a vacuum or a small brush to remove the clog. If it’s tough, mix vinegar and water or use a special cleaning solution made for AC drains. Pour it in and wait for 30 minutes. Then, flush it with water.

And if you have done repairs and need help to restart your AC unit, we have a great article covering how to turn on a central air conditioner. For more of our content, check out how to straighten air conditioner fins, how to winterize an A/C, how to turn off an air conditioner, and how to wire a disconnect box for an air conditioner.


  • A drain clog can be recognized by a slow flow of water coming out of the condensate line or watermarks on the ceiling.
  • Clogged drain pipes often happen as a result of poor air filtration.
  • Keeping your drain pipe unclogged can save homeowners from flooding or water damage.

Insider Tip

To help avoid a clogged drainpipe, clean the filter every 30-60 days.

Unclogging A Blocked Air Conditioner Drain Pipe

When AC air is not filtered correctly, algae, mold, and bacteria build up in the drainage pipe. Because of this, a clogged AC drain line (also known as an AC condensate drain line) can lead to water stains on the ceiling or even flooding. This excess water can lead to mold growth or, worse yet, a full drain pan that can lead to more problems. Fortunately, a reliable repair service can help prevent water backup and musty odors from developing in the first place. They can inspect and clean your AC condensate drain line to ensure no further issues arise.

Such issues are why catching a clog early on can be the difference between a quick, painless fix and thousands of dollars worth of repairs. And for more information on other AC-related questions, we have a great resources on how to unlock an air conditioner thermostat, or if you are wondering why does my AC smell?

STEP 1 Locate the Drain Line

  1. Go outside to your AC unit and find the drain line. Examine it to see how the water flows out.
  2. If the water is dripping very slowly, this is a typical sign of a clogged drain line.

STEP 2 Turn Off the Air Conditioner

  1. Go to the circuit breaker that is outside, near the central AC unit, and turn the electrical disconnect switch off.

STEP 3 Remove the Drain Pipe Cap

  1. Remove the cap and examine the pipe for any debris clogging the system.
  2. If there is any visible debris, gently remove it.

STEP 4 Use a Solution to Dissolve the Debris

  1. After putting on the safety gloves, take a cup of distilled white vinegar or bleach and pour it down the access hole of the drain pipe. Let it sit for 30 minutes.

STEP 5 Remove Debris with Wet/Dry Vacuum

  1. Get out your wet/dry vacuum and attach it to the drain pipe.
  2. For best results, purchase an attachment that adapts a vacuum head to a drain pipe. However, if you don’t have an attachment, you can also wrap rags or paper towels around the pipe to create a seal.
  3. Hold the vacuum hose firmly up to the drain pipe and turn the vacuum on for about 20 seconds.
  4. Check inside the vacuum to see if the clog has been removed.
  5. If the clog remains, call an HVAC professional.


Going through this process won’t always result in an unclogged line. If this is the case, call an HVAC service.


How can I tell if my AC drain line is clogged?

The most noticeable signs of a clogged pipe are lower cooling power, water stains on the ceiling, and an AC unit that drips water or has a moldy smell.

Is bleach or vinegar better for your AC drain line?

Vinegar is a better option because it’s as effective as bleach and has lower health risks.

How often should you put vinegar in your air conditioner?

Putting a cup of vinegar in your drainpipe should be done every month for best results.

STAT: Experts say that, if your lights only lose about 5% of their brightness, this isn’t a sign that someone is wrong with your AC unit. (source)

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