For their own peace of mind, home owners should get their heating and cooling systems cleaned by members of NADCA, who must comply with a strict Code of Ethics.
Some homeowners have been taken by what’s known as “blow-and-go” air duct cleaning. These companies charge what seems a nominal fee but do a very poor job. They may ask you to pay extra for unneeded services and even pretend to be members of NADCA.
You can protect yourself:
Ask the contractor which components will be cleaned.