Read & Follow Instructions to the letter! Wear hand and eye protection!I have two condensers for my home. I made sure the units were turned off before I started and had my garden hose ready.. After 10 minutes, I flushed well with a LOT of water and I followed up with a mild detergent in my garden sprayer. The residue being flushed from the coils was pretty gnarly looking and it took quite a bit of flushing from the inside-out to get it all purged. The results were good, but I have noticed a little oxidation in places. I have since, hit those areas with some WD40 spray and that seems to keep it in check. The AC seems to run a little more efficiently now - which should result in lower electric bill and may also extend the lives of my units.I keep up with my reviews and will update this one if necessary.I give this cleaning concentrate my Big-Foot “Stomp†of approval and 4 stars.