Air Duct Sanitizing in Houston, TX

Does sanitizing the ducts actually fix a musty smell?

Usually not by itself. The odor at startup almost never comes from the branch runs. It comes from the evaporator coil, the return box, and a drain pan holding water. Spraying an antimicrobial downstream of that leaves the source alive. We clean the coil and blower wheel first, clear the drain line, then treat surfaces. Sanitizing a dirty duct is just wet dust.

Material matters too. Houston attics run a lot of insulated flex with a plastic inner core, and that wipes and treats reasonably well. Pre-1980 metal trunk with internal fiberglass liner is different. Once that liner is shedding, a biocide soaks in and the fiber stays degraded. Replacement or encapsulation is the honest answer there, not fogging.

We use products labeled by the EPA for HVAC surfaces and apply them the way the label reads. Anything else is guesswork with a sprayer. Occupants with asthma usually leave during application. We air the system afterward.

Then we go after the cause. Return-side leakage pulling 135°F attic air drags in humidity, dust and insulation fiber. Taped-only boots and open plenum joints get sealed on the same visit. Skip that, and the growth returns before the next cooling season ends.