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HVAC condensation leading to mold

HVAC Condensation and Mold

Condensation on coils, ducts, and drip pans can create hidden mold sources.

Why HVAC Systems Sweat

Cold surfaces in air handlers and ductwork meet warm, humid air and create condensation. If the water is not drained properly, moisture builds up and mold can grow.

High Risk Areas

  • Evaporator coils and drip pans
  • Insulation inside air handlers
  • Ducts running through humid spaces
  • Blocked condensate drain lines

Maintenance That Prevents Mold

  1. 1

    Keep drain lines clear

    Flush condensate lines to prevent backups.

  2. 2

    Replace filters on schedule

    Dirty filters reduce airflow and raise humidity.

  3. 3

    Inspect insulation

    Replace wet or damaged duct insulation.

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3 more maintenance steps

Moisture Control Basics

Moisture inside ducts and air handlers creates the conditions for microbial growth. Prevention focuses on removing standing water and fixing the underlying cause.

  • Keep condensate drain pans clean and draining
  • Fix refrigerant and airflow issues that cause coil icing
  • Remove and replace wet or moldy duct insulation
  • Avoid running the system if contamination is suspected

When to Call a Pro

Monitoring Tips

  • Track indoor humidity near vents
  • Listen for gurgling or dripping sounds
  • Inspect air registers for moisture or staining
  • Use moisture meters near air handlers in basements