I have a two AC units for my 2-story home that are about 15 years old. The internal coils (cooling coils, evaporator coils ?) in my attic have needed cleaning for some time. I know a good cleaning will increase efficiency and probably lower my electric bills. Professional estimates run several hundred dollars for this service here in the Houston area. I am tempted to do this myself, but am unsure how and with what. I know I most likely need some caustic acid solution to remove years of deposit. Can someone walk me through this? I would respond with precise model and pictures if needed. Thanks in advance.

Well, it's not much different than cleaning the coils on the refrigerator. You do have to expose them and vacuum them first.

If you change the inside filter like your supposed to and every year remove the debris from the outside coil, you'll naver have to use a commercial product. Outside, water and haose might all that is necessary.

There are commercial products for cleaning. As an example: http://www.mainsupplies.com/index.ph...FQuwGgodtib6CQ

A new toilet brush will clean your coil best if needed... unless it is so bad a removal of the coil after pumping refrigerant back, and taken to get chemical with a hose... hopefully it isn't that bad... but a good way to keep from cleaning coil is keep filter clean... if you vacuum the fins... make sure you DO NOT bend them over... if you do... you will be purchasing a new fan coil!! If using the Toilet brush... new of course.. go with the way the fins are... do not go against it! Good luck

Make sure you remove all trace of the cleaner. It could very easily cause corrosion.