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How To Clean AC Drain Lines: A Step By Step Guide

Taking time to assess and find out how to clean AC drain lines usually has a great positive impact on the efficiency of your air conditioner.One of the primary functions of an AC system is to remove moisture suspended in the air in your house and make your living environment more comfortable.

The AC system collects and condenses this moisture which drips into a condensation pan. The collected liquid is then channeled outside to a collection point via the condensate drain line.

Common Causes of AC Drain Line Blockages

Dirty AC Drain Line

One of the most common causes of clogged condensate drain lines is the condensed moisture that passes through it.

The condensation passing through the AC system can be filled with dust particles, fungi or even bacteria. If the bacteria is condensed, it often forms a thick sludge or grim than can attract mold.

As all this accumulates, the drain line becomes constrained and may eventually stop working completely once the passage is blocked.

How often the clogging happens depends majorly on how well you maintain your system, the efficiency of your AC air filter and how often you replace it. The condensate drain line can however still become clogged even if you have an efficient filter.

This is because the system traps all manner of particles and so it should be regularly cleaned and maintained regularly.

Cleaning your line removes blockages and clogs and prevents mold and algae from growing. Below is a step by step process on how to clean your AC drain line to avoid this blockage and clogs.

Step 1: Assessing the Need to Clean Your Drain

A condensate drain is working properly if it drips any time your AC comes on. The line is usually located close to the outdoor compressor and it will be made from PVC. If there is no dripping, it might mean that your drain is constrained or blocked.

Some AC systems have an alternative pipe that allows water to be released to the outside in the event of clogging. If you see dripping from the alternate pipe, then chances are your main drain line is blocked and needs cleaning.

Step 2: Collect Tools and Supplies

Unclogging a condensate drain line is not as difficult as you may imagine. You can easily do this on your own with common items found in your home as tools and supplies. At the very least, you will need rags, dry/wet vacuum, distilled vinegar, and funnel.

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Step 3: Turn off Your AC

Turning Off AC

Trying to work on your AC when it’s still running has obvious dangers including injury to yourself and damage to the system. So before you start cleaning your AC system, be sure to switch off at the breaker and the thermostat.

After you’ve switched off the system, locate the condensate pan. You will often find this directly below the unit. Some models have this panel covered with a removable pan.

Step 4: Look out for Standing Water

If there is any water retained on the drain pan, chances are your drain line is clogged. Use a shop or handheld vacuum to remove the trapped moisture. Alternatively, you can soak up the water using rags. You can then use soap to clean up the drain pan.

Step 5: Clear the Clog

You can successfully clear clogged drains by suction. Locate the drain opening outside your house, near the foundation. Using a vacuum cleaner, pull the clog through the drain opening by placing your hand around the drain pipe to improve suction.

Let the vacuum run for at least a minute and check the canister to see of you successfully pulled any clog.

Step 6: Flush the Drain Pipe

First, you will need to locate the access point on your drain line. This is usually a T-shaped vent secured with a PVC cover. Unscrew the cover and take a closer look at the drain.

Use this access point to flush the drain line with distilled vinegar. You can alternatively use hot water with a few drops of dish liquid.

Step 7: Complete the Cleaning

Flushing AC Drain Line

Allow the cleaning solution to sit for about 30 minutes then wind up the cleaning by flushing the pipe once more with clean water.

Let someone watch the drain pipe from the outside and inform you if the water is freely running through the pipe. If not, repeat the process from step 5 above.


As you can see, anybody can learn how to clean AC drain lines using simple tools and supplies found at home. The best part is you can always substitute the items that you don’t have.

Additionally, find out if there are any underlying problems such as a faulty filter, a slightly tilted drain line and so on. The bottom line is to observe regular maintenance and cleaning before the actual blockage happens.

You should read more about How to clean window AC units


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