I am fussy about my Hotend fans. I only use GDS dual ball bearing fans. I had ordered a bunch of them and crimped on the right connectors. I thought I had put them on my new printer which kept clogging. I discovered that I had put the wrong fan on the Hotend, a low output sleeve bearing fan. I put on a GDS dual ball bearing fan and my clogging was gone. It appears that having a high output fan on the Hotend is a must.