You had your HVAC serviced — a refrigerant recharge, a coil replacement, a blower repair — and within weeks a musty smell appeared or visible mold showed up around a vent. Frustrating and confusing. Here's how to sort out what happened and what to do next.
Common ways repair triggers mold
Repairs open the sealed system. If the technician didn't clean and reseal properly, condensation can pool in new places. A refrigerant recharge that leaves the coil colder than the system was designed for creates more condensation. A blower repair that disturbed dust in the ductwork can push spores that were dormant into the airstream. And in older systems, cleaning one area (a coil) without treating an existing colony elsewhere (a drain pan) can simply redistribute the problem.
Immediate steps
Document everything with photographs and dates. Note when the repair was performed, what was done, and when the mold appeared. Get an inspection with air sampling to confirm whether the problem is genuinely new or an existing colony that got disturbed and amplified. This documentation matters for both remediation scoping and any conversation with the original service company.
Talking to the original technician
Reputable HVAC companies will come back to inspect and, when appropriate, cover corrective work. Approach the conversation with your documentation, not accusations — many post-repair mold issues aren't the technician's fault (pre-existing conditions revealed by the repair) but the response reveals a lot about the company's professionalism.
Fixing it properly this time
Whether the technician takes responsibility or not, the mold needs remediation. If the underlying cause is a design issue (undersized system, poor drainage), remediation without addressing that guarantees the problem returns. A good remediator identifies the mechanical fix that needs to happen alongside the biological cleanup.
When to call ProZone
If mold appeared after recent HVAC service and you need an independent assessment, message us on WhatsApp at +52 624 141 6627. Founded in 2014 after Hurricane Odile, ProZone is OSHA and Cal OSHA certified and has remediated some of the most iconic homes across Los Cabos, San José, and Todos Santos. Ask us — we know how.
Jose Lima — Founder, ProZone
OSHA & Cal OSHA certified mold inspector. Serving Los Cabos and Todos Santos since 2014. Member, National Ozone Technician Association.
