Dark residue coming from your fan?

This would be associated with the ionizer on the fan with filter. If this is occurring, the unit likely has an excessive amount of dust built up in the internal components of the fan. We recommend following the below cleaning instruction (https://www.youtube.com/watch?v=OwoUi_esJbY&feature=youtu.be ). This is not an indication of a defect with the fan, but rather that it is in need of a good cleaning.