How often to you clean the air ducts in your home? Generally, it's something that a company that handles HVAC systems should do to be thorough. Experts say that every three to five years you should have them cleaned. Rodents can wander in these ducts and that may have been what attracted the snakes that were found in the Richland home. If you have recurring illness or sneezing, or notice dust around your vents and registers, it's probably time for a cleaning. I have used  A-One Refrigeration and Heating for years and love them. They can take a look at your ducts and determine if you need an immediate cleaning or not.