San Antonio duct cleaners flag hidden mold risk in HVAC systems

America's Best Duct Cleaning says mold and microbial growth inside residential HVAC systems is showing up more often across South Texas, driven by humidity, long cooling seasons and moisture that homeowners may not see until odors or discoloration appear. The company says cleaning alone may not solve the problem if drainage or insulation issues keep bringing moisture back.

Why it matters: - Mold and microbial growth inside HVAC systems can spread through air ducts, registers and other components homeowners rarely inspect. - In South Texas, long cooling seasons and high humidity can keep systems damp for months, raising the odds that growth develops and returns. - The issue can affect indoor air quality and may point to a drainage or insulation problem that needs repair, not just cleaning.

What happened: - America's Best Duct Cleaning says it is seeing more mold and microbial growth inside residential HVAC systems across the San Antonio area. - The company says the problem often shows up in multiple parts of the system, including the air handler, plenum, registers and air ducts. - David Delfeld of America's Best Duct Cleaning said the growth can be seen in those areas and is often hidden from homeowners until other signs appear.

The details: - Moisture is the main driver of growth, especially where water collects or surfaces stay damp between cooling cycles. - The evaporator coil and drain pan are common trouble spots because the coil removes humidity from the air and any drainage failure can leave standing water upstream. - The supply plenum is another concern because cold air meeting duct surfaces can cause condensation. - Ductwork and registers can show discoloration that homeowners may notice without understanding what it means. - Damp insulation is especially problematic because it holds moisture, and dampness plus debris can support growth. - Delfeld said San Antonio's hot, humid climate and long cooling season create ideal conditions for growth inside HVAC systems. - The company says frequent air conditioner use creates condensation on the evaporator coil, drain pan and other air handler components. - Dust, dirt and organic debris entering the system can combine with that moisture and allow mold to develop. - Poor drainage, clogged drain lines and damp insulation can make the problem worse. - A partially restricted condensate line may still drain slowly, which can leave a drain pan holding water longer than intended. - A drain pan sitting in a warm, enclosed space for months can continue feeding growth conditions. - Early signs can include a musty or earthy odor when the AC runs, visible discoloration around vents, excess moisture, water around the air handler or damp insulation. - An odor that appears when the system starts and fades during operation can point to the HVAC system rather than the home. - Water around the air handler usually signals a drainage issue that will keep creating the right conditions for growth until repaired. - Individual sensitivity to mold varies, and the company says it cannot make health determinations. - Homeowners with persistent symptoms are advised to consult a physician. - Homes with extensive or structural growth should involve a licensed remediation contractor rather than relying on duct cleaning alone.

Between the lines: - The company is framing mold in ductwork as a systems problem, not just a cleaning problem. - That matters because visible growth at vents may be only the symptom, while the cause can be a hidden drainage fault, leak or moisture retention in insulation. - The message also suggests many homeowners may underestimate risk because the source is inside equipment they do not routinely inspect.

What's next: - America's Best Duct Cleaning recommends seasonal checks of the condensate drain line before a backup occurs. - The company also advises homeowners to confirm that duct insulation is intact and dry. - Air handlers and plenums should be inspected directly instead of relying on what is visible at the registers. - Cleaning may remove what is inside the system, but the underlying moisture source must be fixed to prevent recurrence. - The company says inspections can be scheduled through its website or by phone.