A water stain on ceilings near ducts may point to condensation, drainage failure, or a disconnected line

https://www.slideserve.com/katterobac/average-air-conditioner-repair-cost-by-brand-and-system-age

A water stain on ceilings near ducts may point to condensation, drainage failure, or a disconnected line. Turn off the system and inspect carefully before calling for repair.