The Angie's List Magazine has done several articles about air duct cleaning.
http://magazine.angieslist...
.The EPA and National Air Duct Cleaners Association both agree: A poor job is worse than
no cleaning at all, as it can kick up particles, damage or even break portions
of the HVAC system.
Check AngiesList.com to find highly-rated air duct cleaners in your area, and be sure to look up NADCA members at nadca.com. Member companies must keep at least one technician on staff who has passed a NADCA test.