I had my AC unit on top of my roof inspected today. The AC guy stated the coil was leaking and explained a process by which cleaning chemicals used every day in the house are recirculated in the AC unit and over time the coil will develop numerous pinhole leaks. He said the term for it was spidervaning. He showed me the outside vanes where there were some streaks he attributed to oil leaking from the coils.
I can't find anything on the internet about this and am looking for advice on whether or not I should be worried.