In the typical home, the equivalent of the complete volume of air in the home passes through the ductwork several times per day. While there are companies offering services to clean these passages, it's possible to do it yourself. Rent a high power vacuum with an extra long flexible hose from a tool rental company for the most effective cleaning.
Turn off the power
Before beginning the job, turn off the power to the HVAC system to ensure your safety. This also prevents the blower from automatically turning on and blowing dust you have loosened from the duct throughout the house before you have a chance to clean it with the vacuum.
Remove register grills
Lift floor registers to remove them. Installers use screws to hold wall and ceiling vents in place. Remove the retaining screws and the vent covers to access the passages.
Vacuum away the dust
Work the hose slowly through the length of the vent to remove any accumulations. If you haven't cleaned the ducts in several years, make more than one pass through the area with the vacuum hose.
Clean the return vents
When cleaning the air delivery ducts, don't forget the return vents. Vacuum the registers, remove them, and vacuum these large ducts. Replace the filter, and turn on the power.