Diag/ water dripping from light in kitchen. Checked system that is closest to this location (unit #1 - serves upstairs, located in upstairs closet attic access), and found it does not sit very close above this area, found primary drain switch and secondary pan are dry. Made sure the lineset or drain line aren’t above this area and drip could possibly be from condensation, but the lineset runs out to the left side of house away from area and drain line runs to back wall. Both are properly insulated. Washed the washable filter and cleared the drain, did get a bit of build up out of drain and I can hear and feel suction from vacuum in the attic. However I cut drain in several places and found a small layer of buildup at bottom of drain that goes along entire line. Used nitrogen and flushed water through line until water came out clean, and drain is currently dripping outside. Told customer I’d like to follow up and preform next maintenance so that I can bring a chemical cleaner and l