"CJT" wrote in message
...

Everything I've read indicates the commercial duct cleaners are mostly
purveyors of snake oil.

Not the guys I had do my last house. They stuck a pneumatic air hose in the
vents with some kind of rotating head on it with some spaghetti-like rubber
bristles about 6-8" long, and put a vacuum thing on the furnace-end of the
system. The air hose thing beat the dust loose and the vacuum pulled it out.

I had it done only because the hardwood floors had recently been refinished,
incl. sanding to bare wood. It had probably never been done before either,
40 year old house.

As another poster said though, your problem probably isn't the dust. It's
either a physical obstruction in a branch supply (or return), or the
furnace's blower is going bad, or some other issue.