How to Get Rid of Slime in Evaporator Drip Pan

Kimberly Johnson

The inside unit of a central air conditioning system is called the evaporator, which sits on top of a shallow metal tray called a drip pan. The purpose of the drip pan is to catch condensation from the evaporator coils and drain the water down a tube to the outside of the home. If you have heavy condensation, the pan may stay wet constantly, which will create algae and slime. You can prevent this with regular preventative maintenance.

  1. Locate the metal door on the outside of the unit and lift it up and out to remove it. Some units are attached with screws you must remove before pulling off the door. If there is a filter in the evaporator, remove it as well. These units are typically installed in attics or in access panels within walls.

  2. Put on disposable gloves and shake up a can of no-rinse evaporator coil cleaner, which is available at janitorial supply companies. Aim it toward the bottom of the unit near the drip pan and spray as much of the pan as possible.

  3. Insert a thin, non-abrasive sponge under the unit and wipe as far as you can into the drip pan to remove the slime. You won't be able to reach the center of the pan, but that's alright because the cleaner will kill the slime there.

  4. Drop two condensate pan cleaner tablets into the drip pan on either side of the unit. These tablets have an anti-fungal ingredient that prevents new slime from forming as condensation enters the drip pan. Replace the tablets every six months, as they dissolve over time.

  5. Replace the filter and the door on the side of the evaporator unit.