How mold gets into an HVAC system
Short answer: HVAC mold usually starts where moisture collects: the air conditioner’s evaporator coil and drain pan, a clogged condensate line, or ducts that sweat in a humid crawl space or attic. The system then circulates odors and spores through the house.
- Clogged condensate drain lines and standing water in the drain pan
- Dirty evaporator coils that stay damp
- Uninsulated or leaky ducts running through a damp crawl space or a cold attic
- Condensation on supply registers in humid rooms
- Return air drawing from a moldy area such as a basement or crawl space
Signs of mold in vents and ducts
- Musty or “dirty sock” smell when the system turns on
- Dark spots on vent covers or the ceiling around supply registers
- Visible growth on the air handler cabinet, coil or insulation
- Water around the furnace or air handler
Dark spots around a vent are sometimes dust deposits rather than mold. Our team can tell the difference and check the system interior.
How HVAC mold remediation works
The order matters: our team normally addresses mold in the home first, then the HVAC system, so ducts are not recontaminated. Work may include inspecting the air handler and accessible ducts, correcting drainage or condensation problems, cleaning the coil, drain pan and blower compartment, cleaning or replacing contaminated duct sections (flexible duct and duct board with growth are often replaced rather than cleaned), and replacing filters. Some steps may involve an HVAC technician.
Spraying chemicals into ducts without removing growth or fixing moisture is not a substitute for remediation. We tell you up front what will be cleaned, what will be replaced and how we will confirm the result.
Find the source first
An odor through the vents does not always mean the ducts are moldy; the system may be pulling air from a moldy crawl space or basement. A mold inspection helps pinpoint where the smell starts, and our musty odor removal page explains other common sources. For an overview of all mold removal services in Caldwell, ID, visit our homepage.
