Evap coil needs cleaning. Repairman was on roof several weeks ago & replaced parallel capacitors. Showed me a pic....very heavy dirt/dust covering most of it...less than half was clear, now it's barely blowing. Assuming it's completely clogged with ice and debris. Planning to go up and clean it & would like to find a diagram of the coil &/or recommendations on the best way to do so. I've seen directions for cleaning with shop vac or a/c foaming cleansers that need rinsed with bleach.