[mgenius33]

I agree with Wayne, the mold thing is bogus. Moisture is related to the temperature of the air and the ambient RH% in the home. If you have supply air temperature below dewpoint then you're likely to have sweating supply grilles.

So what do our brilliant manufacturer engineers come up with to reduce indoor humidity???

Yeah! Let's sell overpriced variable speed blowers that decrease air speed which in turn creates a lower supply air temperature! Great, our indoor humidity level is a whopping 3% lower, and now we have moldy registers!