Came out to call. Customer stated that the system upstairs was doing the same thing. Emergency pan was full of water again and shut the system off. I checked the drain and it wasn’t holding water. I went ahead and added a jones valve and put nitrogen through the line and could hear it clear downstairs. Heard some gurgling in the main drain downstairs below the return. Told customer it may be the main backing up and causing the drain to not drain properly and spill over into the drain pan. I adjusted the fall of the coil a bit more too, to ensure system has enough fall to drain properly. Vacuumed out drain pan and cycled system on. AC is working properly, and thermostat dropped a couple degrees before I left. Told customer this call is on me since I was out not too long ago for the same issue. But I did recommend customer have maintenance drain checked.