How To Unclog A Central Air Conditioner Condensate Drain

Posted on: 15 June 2017

If you don't clean you condensate drain line regularly, it can get clogged. A condensate drain line catches the water that air conditioners remove from the air. 

It is easy to forget to clean the drain, as even HVAC maintenance technicians forget upon finishing a service call. This means homeowners have to stay on top of it.  Here are tips to  unclog  a central air HVAC condensate drain.  

Prepare to Work

For this project, you need:

  • work gloves
  • screwdriver
  • white distilled vinegar or liquid dish soap
  • wet/dry vacuum
  • shovel (optional)
  • 90-degree pipe fitting and pipe piece (optional)

Turn the thermostat to the lowest setting, then shut off the power to the unit from the breaker  box. Find the drain, which is commonly a PVC pipe located under the air handler, on the outside unit, or a utility closet. 

Test for Clogs

Use the screw driver to remove the panel screws, and locate the drain pan under the coils, or lopping pipes. If it is filled with water, it is a good sign of a clog. Proceed to flush the clog.

Otherwise, fill it with water, and look for the drain exit, which is commonly found outside the unit near the copper piping. A slow drip or no drip means a clog.

If you don't see a drain, use a shovel to make a small hole in the area the copper piping extends from the ground. Trace the lines back to the house. If you run into a small pipe, remove the dirt, and connect a 90-degree pipe fitting, a T-shaped vent, and small pipe to it. Otherwise, continue to remove the clog.

Flush the Clog 

Remove the cap from the T-shaped pipe fitting, and attach the wet/dry vacuum hose over the pipe opening, and suck up as much water as possible for about two minutes. Wrap your hand around the pipe to increase suction power. If you don't own a wet/dry vacuum , you may use a small piece of surgical tubing on drains without sharp turns.

Remove the hose, and slowly add a gallon of vinegar through the opening, and let it stand. Distilled vinegar has more acidic properties to destroy the clog than non-distilled vinegar. 

Have someone to watch the drain pipe on the outside to see if the water runs smoothly. Alternately, pour liquid dish washing liquid and hot water in the valve opening. Flush the drain with clean water, then restore power.

You may need to repeat the steps again to clear the drain. Regular cleaning will keep the condensate drain from clogging. If you don't trust your skill, or the drain still seems clogged, contact an HVAC service company.