A light coat of dust in your return vents is normal and logical but, if it bothers you, it can be vacuumed out. Only three problems indicate a proven need to have your air vents professionally cleaned. Otherwise, keeping your air vents clean is mostly a matter of keeping them dry and keeping up with routine maintenance.
A Few Ounces of Prevention
Filters obviously play a critical role in preventing contamination of your venting system. Go with the manufacturer’s recommendations to ensure that your filters are the most efficient ones available. Change them on a regular schedule, and step it up if you notice clogging — because they are what they are.
Take advantage of service calls by professionals performing annual inspections of fireplace and furnace. Ask them to clean your pans and coils and check for missing filters. If there are problems with gaps around the filter holder, they will see that during the inspection. Gaps provide a way for dirty air to dodge filtration and make it into the system.
If you decide to have some remodeling done, close and cover your return vents and supply registers. Keep the system off until the day’s mess has been cleaned up and work areas have been well vacuumed. The most efficient vacuum you can afford is definitely worth it, as less efficient models mostly stir up dust and move it around.
If You Still Need a Cure
If you see mold, excessive buildup of dust in air vents, or evidence of infestation, call a service professional. These are the three things that are cause for the greatest concern because they are proven threats to both safety and system. In these cases, you need to get the whole system inspected and, if possible, cleaned. If mold is spotted, replacement may be needed for health reasons.