Repaired above-ground air ducts by applying a high-performance mastic sealant and aluminum foil tape. Inspected the ducts using a smoke pencil to locate leaks and weak joints. Found several areas with insufficient sealing. Applied the sealant to all joints and gaps, ensuring an airtight seal, then reinforced with tape for added durability. After repairs, verified system efficiency by measuring airflow and pressure with a manometer to ensure optimal operation and prevent air loss.