Most calls about air duct cleaning start with the same handful of questions. Do my ducts need it? What actually happens? Will it make a mess? How do I know the company is legit? Here are straight answers, in the order people usually ask them, so you know what you’re paying for and what to skip.
“Do my ducts actually need cleaning?”
Not always. The U.S. Environmental Protection Agency (EPA) suggests considering a cleaning in three situations:
- You can see substantial mold growth inside hard duct surfaces or on other parts of the system
- The ducts have rodents or insects in them
- The ducts are clogged with dust and debris, or you can see particles blowing out of the supply registers
A few other cases also make sense to look into: you just finished a remodel that threw a lot of drywall dust into the house, you bought a home with no record of duct service, or you have pets and the return grilles keep filling with hair. Light dust on a register cover, on its own, isn’t a reason to clean the whole system. Our post on warning signs your air ducts need cleaning goes through the symptoms in more detail.
“What happens during the cleaning?”
A real cleaning removes the debris from the system instead of just stirring it up. The industry method is source removal. The crew connects a powerful vacuum to the duct system to put it under negative pressure, then loosens buildup with brushes, air whips or compressed-air tools so the vacuum pulls it out.
A complete job covers more than the ducts you can see. The EPA notes that the supply and return registers, grilles, the blower and its housing, the coil and the drain pan should be included. Cleaning only the ducts and skipping a dirty blower or coil leaves a source of dust and odor in place.
“How long will it take, and will it make a mess?”
Plan on part of a day for a typical home. Bigger homes, more vents, attic or crawl-space access and heavy buildup add time.
It shouldn’t make a mess. Expect the crew to cover the floor at the work areas, seal the registers while they work and put the system under negative pressure so dust goes into the vacuum, not into your rooms. You may smell a little dust once the system runs again. That fades quickly.
To get ready, clear a path to the furnace or air handler, move furniture away from the vents and give the crew access to the attic or crawl space if the ducts run there.
“How much does it cost?”
The honest answer depends on the home, so be wary of a quote given before anyone knows the size of the system. The things that move the price are:
- How many supply and return vents you have
- Where the ducts run (attic, crawl space, between floors)
- How much buildup there is, and whether there’s mold or pest debris
- Whether the blower, coil and drain pan are included
- Add-ons you actually need, such as replacing damaged duct sections
Our air duct cleaning pricing guide for California explains how quotes are usually built. Whatever company you call, ask for the price in writing and ask what’s included.
“How can I tell a legitimate company from a bait-and-switch?”
The EPA specifically warns about very low “whole-house” specials and about companies that make health claims they can’t back up. Watch for these red flags:
- A rock-bottom advertised price that grows once the crew is inside
- No mention of cleaning the blower, coil or registers
- Pressure to buy a chemical treatment or “sanitizer” before anyone has shown you a problem
- Claims that duct cleaning will cure allergies or cut your bills by a set amount
- A crew that can’t show you the before-and-after condition of the ducts
A good company will tell you what they found, show you photos or let you look, and tell you when cleaning isn’t needed.
“What if they find mold?”
Ask to see it. The EPA notes that something that looks like mold isn’t always mold, and only a lab test can confirm it. If there is real mold growth, the moisture problem that caused it has to be fixed too, or it will come back.
One more detail matters here. Ducts lined with fiberglass insulation, or made of fiberglass duct board, can’t be cleaned well once that insulation is wet or moldy. Those sections usually need to be replaced instead. If you’re dealing with a musty smell and aren’t sure where it’s coming from, read our post on musty HVAC smells: mold or wet insulation.
“Should I use a sanitizer or sealant?”
Only if there’s a specific reason and you understand what’s being applied. The EPA advises learning about any chemical biocide or sealant before you agree to it. Ask for the product name and label, how it’s used and why your system needs it. Sealants are not a substitute for repairing damaged or leaky ducts.
“Can I just do it myself?”
You can do the routine parts: change the HVAC filter on schedule, vacuum the register covers and keep the return grilles clear. You can’t clean the inside of the duct system with a household vacuum. Without negative pressure and the right tools, you tend to loosen dust and push it further in. See our comparison of professional vs DIY air duct cleaning for more.
“Is this the same as dryer vent cleaning?”
No. Air ducts carry heated and cooled air through your home. The dryer vent carries hot, damp, lint-filled air outside. They’re separate systems with different risks. A clogged dryer vent is a fire hazard and should be cleaned on its own schedule. Here’s a full breakdown of dryer vent cleaning vs air duct cleaning, and a list of signs your dryer vent is clogged.
Frequently asked questions
How often should air ducts be cleaned?
There’s no fixed schedule for every home. Clean them when there’s visible mold, pests or heavy debris, after major renovation dust, or when an inspection shows buildup. Homes with pets or smokers may need it more often.
Will duct cleaning help with allergies?
It can remove dust, pet hair and debris from the system. But the EPA notes that duct cleaning hasn’t been proven to prevent health problems. Regular filter changes and controlling dust at the source matter just as much.
Do I need to be home during the cleaning?
Someone should be home when the crew arrives and when it finishes. The crew needs access to the vents, the furnace or air handler and any attic or crawl space. You’ll want to see the results before they leave.
Will cleaning lower my energy bill?
Clearing a clogged blower or coil can help the system move air the way it should. A company shouldn’t promise a specific savings amount. Leaky or crushed ducts waste more energy than dust does, and those need repair, not cleaning.
What should I ask for after the job?
Ask for before-and-after photos, a note on what was cleaned (including the blower and coil) and any damage they found. Ask them to point out any duct sections that should be repaired or replaced.
Want a straight answer about your ducts?
5 Star Air handles air duct cleaning and dryer vent cleaning for homes across Southern California, including Los Angeles. Call (800) 686-5038 and tell us what you’re seeing. If your ducts don’t need cleaning, we’ll say so.