Why Are My AC Vents Sweating? Causes & Solutions If your AC vents are sweating, you’re not alone—this is a common issue in Southwest Florida’s humid climate. Why Are My AC Vents Sweating? Causes & Solutions What Causes It? Sweating vents happen due to condensation. When humid air meets the cold air from your AC system, moisture forms on the vent—leading to visible water droplets. Common Causes High indoor humidity Very cold supply air Leaky ductwork Poor insulation Oversized