Arrived in Smithville for AC Maintenance, Today I arrived and found primary flood safety triggered, however drain pan dry. I stress tested drain using 2 gallons of water, system flows well. I then checked indoor heat exchanger and found that it’s clean, filters are dirty but not terribly, system cooling pressures are completely on target. I think the drain may have been clogged by sludge at one point or another and as the day progressed worked its way out. Customer will keep an eye on it and call if issues persist.