Looked at a heat pump condenser today, mfg’d 2003. Fins of the unit were uniformly dark colored, except in a 1/2" narrow vertical strip, galvanized color, at beginning of fins / coils. Is this a sign of leakage? or average for unit after several years use?
In the pic, the protective grating shows better than the fins.
I don’t see a sign of leakage in the pic you provided. Many times, a leaky spot in a coil will show up as a dusty/oily spot. The discoloration may have more to do with the kind of dust that passed through the fins, or even with what might have been used to clean the coils…such as mixture heavy in acid content. If there is a big pin oak or pecan tree nearby, the tanic acid from their leaves will get into the soil, and over time dust ripe with tanic acid can discolor the aluminum fins. Just something I’ve observed, and may have nothing to do with this case.