I designed this double fan to eliminate the problems of extrusion of the filament caused by overheating the cartridge, the problem occurs especially when printing soft materials.
To fix the fans use M3x14 screws
Finally, once the PID has been set up, use the following command M303 E0 S200 C14 and set the Kp Ki and Kd parameters returned by the tuning with the command M301 Pxx, xx Ix.x Dxx.xx

https://youtu.be/Xuvk28pnaIw

REV 18.1.2018 Restricted the flow slit connected to the heat sink to prevent air from reaching the hotend