The next air conditioning maintenance step to think about involves one of your air conditioner’s fundamental components, the evaporator. The evaporator coil is mounted inside the AC housing and functions as a kind of refrigerator so to speak; sucking in warm air and converting it into cold air before pushing it out the AC vents.

The evaporator usually requires once a year cleaning. With some ACs, the evaporator may not be easily accessible, in which case, you should only get it done by a qualified AC technician. It’s the evaporator coil that your filters are trying to keep clean.  A dirty coil is the number one cause of AC repair calls in the San Fernando Valley.

The evaporator is found directly above the furnace in the plenum. If this plenum has foil-wrapped insulation on the front, you can conveniently clean it yourself. If the plenum is in a sealed sheet metal box, do not attempt to do this yourself.

Now, let’s get to the good stuff:

  •  The foil at the front of the plenum is most likely taped firmly. Gently remove it, since you’ll be putting it back after cleaning is complete. Locate the access plate which is held together with several screws. Remove these and lift off the plate.
  • The underside of the evaporator unit should now be visible; clean it with a firm brush. If you can’t reach all the way to the back of the unit, you could slide the evaporator out just enough to access that part. Alternatively, you could use a mirror as well to see hard to reach areas. If you find yourself sliding it out, be careful; the evap. core/unit has rigid pipes connected to it, do not bend these.
  • Next, clean the tray that’s below the evaporator, which draws away condensation from the evaporator. A tablespoon of household bleach into the weep hole in the tray does a good job of preventing fungus growth. You ought to check the condensation drain and pan every two days or so, in case you have humid weather. Too much moisture in the pan may lead to the drain line getting clogged; you can unclog the weep hole with a flexible but firm piece of copper wire.
  • After this, the evaporator unit needs to go back; reinstall the plate and put tape insulation back over it.

These steps combined with the condenser cleaning that we covered here:, and you can call your air conditioner ready for a long winter’s nap.

If this is just more attention and time than you care to handle on your own, call us at American AC Heat Plumbing and we will be happy to handle these air conditioner services for you – (310) 419-8902.

This article was provided by American AC Heat Plumbing. Since 1981, American Air has been providing professional air conditioning and heating service and repair. Check out their $99 tune-up special – good for your air conditioner or furnace!


James Smith

As you can tell from our humble beginnings in 1981, we began as a family-owned business and stayed a locally owned air conditioning and heating company in Los Angeles county for nearly 40 years.