surely he meant to use the soapy water on the outside of the evap ,not in it.Moisture and air will cause problems if left in a system,the smaller the system the worse the problem.If you dont use a vac. pump after you make the repair you will have moisture and air in it.citrus cleaner,409,simple green all should clean it ok ( externally).most of the internal flush stuff is a mixture of propane,or butane and refrigerant.

oh what a feeling:
#1 86 xtra cab 22R,EB 261 cam ,Hooker header,2" ex with cherry bomb, Aussie powered
#2 86 sr5 4x4 efi parts truck
#3 87 2wd parts truck
84 supra yard art