Clogged AC Condensate Line Signs Vacuum Vinegar Flush Signs your AC drain line is clogged include water backing up around the indoor unit, wet floors or ceilings, the air conditioner shutting off unexpectedly, and visible water at the outdoor termination point; check the condensate drain pan for standing water, smell for mold or mildew, inspect the outdoor drain exit for slime, and perform a wet vac and vinegar flush to clear minor blockages. Use keywords: clogged AC drain line, condensate drain