How do you recommend that I clean a dirty evaporator coil? I appreciate your help!

It depends on how you can gain access to it. You could use water, rinseless coil cleaner or a vacuum. Possibly compressed air but you want to be careful that you don't bend the fins.

On a 2 1/2 ton system or less you can wash it out after applying an alkali coil cleaner or Easy-Off oven cleaner, the type made of lye and that foams up. Use plenty of water and vacuum it up below the coil. If you were a technician you would remove the coil and pressure wash it. If the coil is more than a 2 1/2 ton coil you really need a pressure washer at 1500 psi and a fan spray tip to keep from bending fins. Don't neglect to remove blower unit and clean it as well, but remove motor from blower wheel before cleaning. This is a wet and dirty job best done by a pro. Air and brushes will never work on an AC coil. It takes a good foaming cleaner made of liquid sodium hydroxide which will remove your skin if you do not wear protective gear. DrTom4444