AC Ducts and Residential Air Quality
Central air conditioning uses the same duct network as your heating system. That means everything that accumulates in your ducts during the heating season — dust, pet dander, debris from construction work — circulates through the house when you turn on the AC in late spring. In New England, where heating season runs from October through April, the accumulation question is real.
AC duct cleaning is essentially the same service as general HVAC duct cleaning, with particular attention to components that see the most moisture during cooling season: the evaporator coil, the drain pan, and the first few feet of supply ducts near the air handler. Condensation on cold duct surfaces during humid weather can create conditions for mold growth if dust is present, so those areas warrant closer inspection.
When AC Duct Cleaning Makes Sense
The most clear-cut cases are: visible mold in the air handler or on accessible duct surfaces, a musty smell that appears when the AC runs (and that smells different from normal dust), evidence of pest activity in the ductwork, or a home that's had major renovation work done without good dust containment.
Moving into a previously-owned home is another strong candidate. You don't know how the prior occupants maintained the system, whether they had pets, or whether there were any moisture events during their tenure. Starting with a clean system is reasonable peace of mind.
What the Cleaning Covers
A complete AC duct cleaning covers the supply and return duct networks, the air handler cabinet, the blower wheel, the evaporator coil (cleaning or at minimum inspection), and the drain pan. If your contractor is only doing the registers and visible duct openings, that's not a full cleaning — it's a start.
NADCA-certified contractors are trained to address the full system rather than the visible parts. That's the benchmark worth using when you're comparing companies.
What It Doesn't Fix
Duct cleaning won't compensate for an undersized filter, a leaky duct system that's drawing in unconditioned air, or a coil that needs professional cleaning or replacement. If your AC system has airflow problems or efficiency issues, those have separate diagnoses. A cleaning may reveal those problems, but it won't solve them on its own.