They make a spray foaming cleaner sold at Lowe's and home depot. It is about $5.00 a can. It is supposed to lift the grime and gunk and make it easier to wash away. I bought 2 cans last month that I plan to use next time I clean the coils. I do it about once a month in this weather. Fighting the dirt and cotton woods! Has anyone used the can cleaner and what are your thoughts?