Vacuum supply vents and return grilles every month or 2, and take the covers down to wash a few times a year. Check the AC filter monthly and change it when it is dirty. Routine duct cleaning is not usually needed: the EPA suggests it only for substantial visible mold inside the ducts, an insect or rodent problem or heavy dust and debris.
Supply vents and return grilles
Supply vents blow cooled air into each room. The return grille, often a larger grille in a hallway ceiling or on the AC closet door, pulls air back to the unit through the filter. The EPA notes that it is normal for return grilles to get dusty as air is pulled through them, and that this does not mean the ducts are full of dust.
How to clean vent covers
- Turn the AC off at the thermostat
- Vacuum the cover with a brush attachment
- If the cover unscrews easily, take it down and wash it in warm water with dish soap. Dry it completely before you put it back
- Wipe the ceiling or wall around the vent, where dust and damp collect
- Fix the cover back firmly and turn the AC back on
Do not push water, steam or sprays into the duct itself. The EPA says steam cleaning and other methods involving moisture should not be used on ductwork.
The filter
- ENERGY STAR advises inspecting, cleaning or changing the filter once a month
- Use the highest efficiency filter the system maker recommends, the EPA says, in the size printed on the old filter
- Make sure it fits with no gaps, so air cannot bypass it
- Pets, sand and a long cooling season mean it clogs sooner, so change it more often if it does
Mildew and condensation around vents
In humid months, moisture can collect on a vent cover and the ceiling around it, and dark spots there are usually dust and mildew. Wipe them with detergent and water and dry the area. The EPA says condensation on surfaces can be a sign of high humidity. If spots come back quickly, the vent drips or the ceiling stains, there may be a problem with the duct insulation, the AC drain or the humidity in the home, and that needs an AC technician. Our mildew guide covers keeping humidity down.
If you know or suspect there is mold inside the AC system, the EPA says not to run it until it has been dealt with.
When duct cleaning is worth it
The EPA suggests considering duct cleaning when:
- There is substantial visible mold inside hard ducts or on other parts of the system
- The ducts are infested with insects or rodents
- The ducts are clogged with heavy dust and debris, or dust blows out of the vents
The EPA does not recommend routine duct cleaning, and says it has never been shown to prevent health problems. Fix the cause first, such as a leak or a drain pan that does not drain, or the problem is likely to come back. Duct cleaning is specialist work and is quoted separately from house cleaning.
Tenants and landlords
In most rentals the tenant keeps the vent covers clean and changes the filter if the lease says so, and the landlord services and repairs the AC system itself. Florida's landlord maintenance law, section 83.51, does not mention air conditioning, so your lease sets out who does what. Report leaks, dripping vents, a blocked drain line or an AC that stops cooling to your landlord in writing, and keep a copy.
This guide is general information, not legal advice. Laws change, and your lease may add terms. For advice on your situation, speak to a Florida attorney or the Legal Aid Society of Palm Beach County.
A deep clean includes ceiling fans, light fixtures and AC vent covers. Send a request and a local cleaner will call you to quote.