Short answer: schedule an HVAC duct **inspection once a year** and **clean as needed** based on what the inspection finds. That “as needed” depends on your home: pets that shed, recent renovations, smokers in the household, water damage, visible dust/debris at registers, or allergy/asthma concerns all accelerate the timeline.

Signs you likely need a full cleaning now:

• Dust build-up on supply/return grilles that returns quickly after cleaning.
• Musty or stale odors when the system turns on.
• Visible debris inside ducts, matted dust on blower/coil housing.
• Recent remodeling or drywall work (fine dust travels everywhere).
• Occupants with allergies/asthma reporting more symptoms indoors.

What “proper cleaning” looks like (in plain English):

• Source removal: dislodging contaminants (brushes/air whips/compressed air) and capturing them with a powerful vacuum under negative pressure.
• Full-system approach: supply ducts, returns, trunks, blower, coil (where applicable), and plenums— not just the vents you can see.
• Verification: before/after photos, access covers resealed, and airflows restored.

Pricing & time: the scope depends on system size, accessibility, contamination level, and crew size. Get a written estimate after an in‑person assessment. If you’ve had renovations, pets, or a lot of visible dust, plan on a deeper project.

Pro tip for NJ homeowners:

• Keep filters clean (check monthly during peak seasons).
• If you see unusual dust reappearing fast, book an inspection first—don’t guess.
• Keep records (service dates, before/after photos). It helps track when the next cleaning is due.