What happens during an air duct cleaning, and how long does it take?

Updated November 10, 2026 · KeystoneProGuide editorial team

What happens during an air duct cleaning?

In a proper job the company inspects the system, opens it up, puts it under suction, loosens the debris with brushes or compressed-air tools, cleans the equipment as well as the ducts, closes everything up and shows you the result. Published estimates of the time range from two to eight hours.

The steps below draw on the U.S. Environmental Protection Agency's (EPA) account of what to expect from a provider and on the method described by NADCA, the industry's trade association.

How should you get ready?

Angi suggests clearing furniture and other obstacles away from the places where the crew needs access. Have the written agreement to hand as well. The EPA says it should state the total cost and the scope of the job before work begins.

The EPA also suggests a step most people would not think of. Show the company its post-cleaning checklist before work starts, so that everyone knows how the job will be judged at the end.

What are the steps on the day?

1. Inspection. The EPA says the provider should inspect the system before cleaning to make sure there are no asbestos-containing materials, such as certain insulation or register boots. If there are, they should be left to specially trained and equipped contractors. NADCA says a contractor should carry out a thorough inspection and tell you about any problems.
2. Protection. The EPA says the provider should protect carpet and household furnishings.
3. Access. Access ports or doors are opened so the entire system can be cleaned and inspected. NADCA says existing openings should be used where possible and that technicians may need to cut access holes in the ductwork.
4. Suction. NADCA says the whole system is placed under continuous negative pressure with a vacuum collection device. The device may be mounted on a truck or trailer, or be a portable unit brought indoors. The EPA says the vacuum should exhaust particles outside the home, or be HEPA equipment if it exhausts inside.
5. Agitation. Debris is knocked loose. NADCA lists brushes, air whips and compressed-air nozzles. The EPA describes well-controlled brushing together with contact vacuuming, and says only soft-bristled brushes should be used on fiberglass duct board or fiberglass-lined ducts.
6. The equipment. The EPA says duct cleaning covers the heat exchanger, heating and cooling coils, condensate drain pans, fan motor and housing and the air handling unit, as well as the supply and return ducts, registers, grilles and diffusers.
7. Closing up. The EPA says access holes should be sealed and re-insulated so they are airtight, and the registers firmly reattached.
8. Walk-through. The provider shows you each component.

What should not happen?

• Steam or wet methods. The EPA says they should not be used on any kind of ductwork.
• Chemicals you did not agree to. The EPA says biocides and sealants should be applied, if at all, only after the system has been cleaned of visible debris, and only if you understand the pros and cons. NADCA says antimicrobial treatment is not part of a typical job for most homeowners.
• Dust in the house. The EPA warns that an inadequate vacuum collection system can release more dust and contaminants than leaving the ducts alone. Michigan's Attorney General has described cut-price operators leaving dirt blown onto drapes, carpets and furniture.
• A token job. NADCA uses the term blow-and-go for companies that charge a nominal fee and do a poor job.

How long does it take?

The published estimates do not agree, which suggests the answer depends on the house.

• HomeGuide: around 2 to 4 hours for a whole system with a two-person crew.
• HomeAdvisor: two to five hours, depending on the size of the home and the complexity of the duct system.
• Fixr: most jobs take 3 to 6 hours, and most cleanings around five.
• Angi: most jobs take 3 to 8 hours. A tip on the same page says five to seven hours on average.

NADCA gives no figure. It says the time depends on the size of the home, the number of systems, how accessible they are, the level of contamination and the number of technicians, and that a contractor should be able to give you a general estimate during a first phone call.

How do you check the job before you pay?

The EPA says a thorough visual inspection is the best way to verify the work. Every part of the system should be visibly clean, with no debris you can detect with the naked eye. NADCA says the same: if any dust or debris can be seen, the system should not be considered cleaned.

The EPA's checklist turns that into questions. Among them:

• Did the provider get access to and clean the whole system, including drain pans, humidifiers, coils and fans?
• Is the heat exchanger surface visibly clean?
• Are both sides of the cooling coil visibly clean, and does light from a flashlight shine through it?
• Is the drain pan clean and draining properly?
• Are the blower blades clean, and the blower compartment free of visible dust?
• Are the insides of metal ducts free of visible debris at several spots chosen at random, on both the supply and return sides?
• Is any fiberglass material in good condition, without tears or abrasions?
• Are new access doors fixed with more than duct tape, and do they leak very little air with the system running?
• Are the registers and grilles clean and firmly back in place?
• Does the system work in both heating and cooling modes?

The EPA says a no to any question may indicate a problem, and that you should ask the provider to correct deficiencies until every answer is yes.

Some providers document the inside of the ducts with remote photography, which helps with the sections you cannot see. NADCA's standard also describes formal verification methods, including a surface comparison test and a vacuum test.

What happens after the crew leaves?

The system should simply work. The EPA's checklist ends with the system running properly in both heating and cooling modes. Keep the written agreement and any photographs.

What keeps the result is ordinary maintenance. The EPA says to use the highest efficiency filter your system's manufacturer recommends, to change it regularly, and to keep water out of the system.

To prepare for the visit, questions to ask before you hire covers what to settle in advance, and air duct cleaning scams to avoid describes the shortcuts to watch for. Local businesses are listed on the air duct cleaning directory page.

Sources

1. Should You Have the Air Ducts in Your Home Cleaned?, U.S. Environmental Protection Agency
2. Why Hire a NADCA Member?, National Air Duct Cleaners Association (NADCA)
3. FAQs, National Air Duct Cleaners Association (NADCA)
4. Cost & Time Estimates, National Air Duct Cleaners Association (NADCA)
5. NADCA Releases 2025 Edition of ACR, The NADCA Standard for Assessment, Cleaning and Restoration of HVAC Systems, National Air Duct Cleaners Association (NADCA)
6. How Much Does Air Duct Cleaning Cost? [2026 Data], Angi
7. How Much Does Air Duct Cleaning Cost in 2026?, HomeAdvisor
8. How Much Does Air Duct Cleaning Cost? [2026 Data], Fixr
9. How much does air duct cleaning cost?, HomeGuide
10. AG Nessel Warns Michigan Residents About Air Duct Cleaning Scams, Michigan Department of Attorney General