How To Clean An Evaporator Drain

Posted on: 18 May 2017

Maintaining your air conditioner is essential in order to keep it running as it should year after year without fail. Things like changing the filter each month, keeping furniture and other items away from the vents inside your home, and removing plants and shrubbery from around your outside unit should all be done to keep your unit running properly.

One thing you may not have thought about though is cleaning the evaporator drain. The drain is responsible for removing the condensate from the humidity that comes into the unit, cools on the coil, then the condensation drips onto a pan, which then runs through a small pipe/drain out of your home, or to a floor drain (or wash tub). Wherever the pipe ends at your home, it can become clogged over time, and could lead to a big mess. See below for instructions on how to clean it.

Here's What You'll Need:

  • Shop vacuum
  • Duct tape
  • Rag


  1. Find the evaporator drain, which may be a piece of white PVC piping that runs from the evaporator coil enclosure and outside of your home, or to a floor drain, or wash tub. If you have an attic unit, it may run down the wall outside of your home. 
  2. Once you find the drain pipe, take a look inside. The pipe may be clogged with algae, mold or other types of growth and debris. This is the clog you are going to need to remove. The easiest way to do so is by using a shop vacuum.
  3. To begin with, turn off the power to your system.
  4. Next, either duct tape the drain pipe to the extension of your shop vacuum, or place a rag around the extension and the drain pipe, then turn on the shop vacuum. Be sure to remove the filter in your shop vacuum to make cleaning the vacuum a little easier.
  5. Allow the vacuum to run for a few minutes, then check the inside of the vacuum to see if anything came out. Also take a look at the pipe to see if you see any algae or other growth inside the pipe. Run the vacuum for another few minutes until it's clean.

Cleaning an evaporator drain is an important step in maintaining your air conditioning unit. A plugged drain can flood your floor, or cause the unit to stop working - either way, it isn't good. Be sure to clean your evaporator drain often to keep algae and other growth from building up. If that doesn't do the trick, try contacting an HVAC service near you.