I'm printing a job of a character holding a staff at various sizes. At 2" tall the model prints fine. A little larger, it's fine. But jump to 6 inches tall and the prints failed repeatedly.
...wait a minute.
Sure enough that's when this model's prints started succeeding. So I pulled the fan duct off so that I wouldn't have to remember to turn the fan off with every print (and moved the printer back into the cold garage so it's effect was less necessary) until this job was finished.
Cooling fans. Sometimes they really improve a print, but sometimes, when making tall towers, they can be the death of them. Go figure.