Jun 18, 2018

How Can I Tell If My AC Drain Line Is Clogged? 

Some newer HVAC units have sensors that will alert you if your AC drain line is clogged so you can fix the problem before there’s any water damage. If your unit isn’t equipped with this technology, you’ll know the AC drain line is clogged because the drain pan is full of water. Make it a habit to check your drain pan whenever you change the filter, so you can catch any issue right away.

Why Is My AC Drain Line Clogged?

The AC condensate drain line removes the water released when the evaporator in your AC unit converts refrigerant from a liquid to a gas. (Learn more about your HVAC system here). Over time, algae and other muck can build up. This may lead ot an AC drain line clog if you don’t maintain your AC unit regularly.

Luckily, unclogging and cleaning the AC drain line is easy to do with tools you probably already have in your cleaning closet. Here’s how to clear up any AC drain line clogs in less than an hour.


  • A stiff, thin wire brush
  • A wet/dry vacuum
  • Duct tape
  • Bleach
  • Rubber gloves


  1. Turn off the power to your HVAC unit. You should always turn off your HVAC before you clean it.
  2. Find your AC drain line. Most AC drain lines are located outside, near the condenser unit.
  3. Push the stiff, thin brush into the end of the drain line. This might clear any clogs located near the end of the drain line. In most cases, the AC drain line clog will occur farther down and you’ll need to do a little more work.
  4. Attach the end of your wet/dry vacuum to the end of the AC drain line. Seal it securely using duct tape. Turn the vacuum on to suck out any debris and hopefully clear your clog.
  5. After you’ve run the vacuum for about a minute, remove the wet/dry vac and head indoors. If the drain pan is full, vacuum it out and clean it with soap.
  6. Locate the vent tee. This is a pipe fitting that connects your AC drain line to the drainage tray. Remove the PVC cap from the top of the vent tee.
  7. Poke that stiff, thin wire brush through this end as well, so you can clean out any easily reachable AC drain line clogs.
  8. Put on your gloves and pour a mixture of one cup bleach and one cup water into the top of the drain pipe. (Make sure you follow safety guidelines for working with bleach.) Wait thirty minutes.
  9. Have a helper stand outside and watch to see if water drains out of the AC drain line. Working alone? Place a bucket at the end of the drain line to see if you’ve cleared the AC drain line clog.
  10. Pour water into the vent tee, and head outside to see if it made it all the way through the AC drain line. If it has, great! You’re done cleaning the AC drain line and you’ve cleared up the clog!

If these steps don’t help when your AC drain line is clogged, then it’s time to call in the big guns. The technicians at Newcomb and Company can clear your clogged AC drain line and make sure you don’t have any other issues causing your AC unit to malfunction. Contact us now to get your HVAC unit into tip-top shape.

Need help? Call now.