Why does my part-cooling fan cause stringing?
Prior to a move the print cooling fan causes the filament to cool on the outside while the nozzle is still hot, when it then moves it causes a strings to form that will be cooled instantly. This means that the cooling you have is too much and should be reduced.

This printer has a single fan to cool the cold-end and the print through a slot with the same fan. As this fan can be scheduled, it would be recommended to create a dual fan on the carriage where you have a dedicated fan cooling the cold end at a fixed voltage, while the print is cooled by a separate fan that can be scheduled through slicer settings.