[Chatbrat]

You don't clean them, use good air filters, if our air filters are doing their job, your ducts don't need cleaning--do a little research on duct cleaning--one of the biggest rip off scams ever It has suddenly bloomed into a billion $$ scam-- your air quality will not improve after getting your ducts cleaned

Better choice-get your house checked for mold & indoor air pollution-not cheap but worth it' we did that when we had bought a condo , that wasn't lived in & the power was turned off for a considerable period of time.