Mold can grow in drain pans, on coils, and in ducts, especially ducts running through damp crawlspaces. The EPA advises not running a system you suspect is contaminated. Here's how that plays out in Rohnert Park & Cotati, what to do right now, and how to reach an independent, licensed local provider. Call (628) 336-1777 any time, or use the form on this page.
HVAC and duct mold in Rohnert Park & Cotati: what we see
Rohnert Park's similar-age homes often have original or second-generation ductwork that may be leaky.
Many Rohnert Park homes have similar-age heating systems and ducts, and older ductwork may leak or have damaged insulation, especially in crawlspaces.
The local picture
Heating systems in local homes. House age and type determine what heating systems and ducts are common. Rohnert Park & Cotati has Rohnert Park homes built in waves since the city's founding as a master-planned community, and in Cotati, older homes near its downtown alongside newer neighborhoods.
Neighborhoods include Rohnert Park's lettered sections, the area around Sonoma State University, and downtown Cotati. Conditions vary from street to street, so a provider should look at your specific home rather than assume.
What to do right now
- Turn off the system if you suspect mold in it.
- Note where the musty smell is strongest and when it happens.
- Check the filter and drain pan, if accessible.
- Don't spray chemicals into the ducts.
- Call an HVAC professional or mold provider for an inspection.
Want a local pro to take a look?It's free for homeowners and there's no obligation.
Rohnert Park & Cotati checklist
- Have older ducts inspected.
- Change filters on schedule.
- Keep condensate lines clear.
- Seal and insulate ducts in crawlspaces.
- Control crawlspace humidity.
Local resources for Rohnert Park & Cotati
- Permits: City of Rohnert Park or City of Cotati
- Emergency alerts: SoCoAlert, the County's free notifications
- Sandbags: Sonoma County sandbag locations, updated during weather events
- Contractor licenses: CSLB license check
How a provider handles it
An inspection finds where growth is and why. The fix may include cleaning components, replacing lined or damaged ducts, and correcting the moisture source. For the full picture, read our complete guide and the deep dive Mold testing: what California says. We also have a storm-season article: Mold in rental housing.
Before you hire anyone, check the license on the CSLB site. Here's how we vet providers.
Dealing with this right now?Tell us what's happening and we'll connect you with an independent local provider.
More for Rohnert Park & Cotati
- Mold removal in Rohnert Park & Cotati: our full local page
- HVAC and duct mold service
- Crawlspace mold in Rohnert Park & Cotati
- Attic mold in Rohnert Park & Cotati
- Bathroom mold in Rohnert Park & Cotati
- Mold after flooding in Rohnert Park & Cotati
- Same problem nearby: HVAC mold in Santa Rosa, HVAC mold in Petaluma, HVAC mold in Sebastopol
- HVAC and duct mold in every Sonoma County town
Sources
Sources checked October 18, 2026.
Frequently asked questions
Do old ducts cause mold?
Leaky ducts in damp spaces can collect moisture.
When should ducts be replaced?
When they're damaged, leaky or contaminated. An HVAC contractor can assess yours.
Will duct cleaning fix mold?
Cleaning addresses existing growth; moisture control prevents it. See EPA guidance.
Who should I call?
An HVAC contractor (check their CSLB license) or a mold remediation provider, depending on the scope.