The mold that you can see is most likely just the beginning of the problem. Mold is a very invasive plant that spreads very easily and quickly throughout a home and starts to grow on any source of moisture. Mold releases seeds or “spores” into the air that are carried around by your AC unit; so if you can see mold, you can bet that it has released spores into the air and the spores have already found a new place to grow (behind walls, on cloths, in the AC unit, under sinks etc.)