Air Duct Repair in San Juan Capistrano, CA

When one bedroom stays hot and the registers keep shedding dust

That bedroom is usually at the end of a flex run. The elbow at the boot got crushed during a truss-bay pull. Airflow drops, and the room never catches up. Sagging flex is the other half of it. The liner bellies between bays and dust settles in the low spots. You feel it when the blower kicks on.

Repair starts at the boots and collars. Duct tape dries out and lets go at the fitting. Mastic and mechanical fastening hold where tape failed. Platform returns are the quiet problem here. Unsealed framing pulls attic air straight into the return. Builder-grade filter grilles are often undersized for system CFM, so dust bypasses the filter edges and coats the coil.

Local conditions add their own damage. Marine-layer months bring condensation and surface mold at bathroom and north-facing supply boots. Near the coast, salt air corrodes registers and metal collars. Hillside grading drives fine mineral dust into attic runs. Rodents chew liner where attics back onto open space.

Older pre-1975 homes may still have rigid sheet metal trunks with duct board plenums. As the binder ages, those plenums shed fibers, and cleaning alone will not stop it.

Open your return grille and look at the filter edges. Gray streaks there mean bypass, not a dirty filter.