I know I’m late to the party, but I managed to fix my Lulzbot Taz 6 Duel Extruder v3 heat creep issues by replacing the 40mm fan that comes shipped with an 80mm fan from noctura. The modification uses all the same bolts as the original fan and secures the new fan to the converter with the rubber bits that come with it. I directly swapped the wires that went to the old fan into the new fan. Before this I spent several months tinkering with settings with no success but with this modification I got perfect prints in PLA and PVA with default settings in my first print. I have since run prints which continued without error for over 24 hours. I’ve attached the modification plans and the STL of converter/duct I am using on my printer. The one I have installed is printed in PETG.
Fan I used: https://noctua.at/en/nf-a8-5v