Ender 3 Pro clogging mystery

Continuing the discussion from Well, it's finally happened…the question is what do I do now?:

Hello this is my first post so I thought I would share my exp with my Ender 3 pro. I have printed tons of small prints these last 2ish years. I started to have clogging problems which have taken me down the rabbit hole of calibration horror. Hotend, bowden tube, filaments…till I noticed, one day while trying to print again, my fan! The hotted fan would vary its speed at times, sometimes stopping for a moment then spooling up. Heat creep was the overlying issue but not easy to see unless you are stareing at the fan for some time. Amazon then sold me a Ceality replacement. That NEW fan too, had the not-run-100% of-the-time issue and caused heat creep and clogging. I’m ordering another:( With luck it will work. Hope this helps someone!

First off do this fix, that usually solves most hot end problems for boden tube printers

I have had similar issues with these very inexpensive fans! I have found that the “sleeve bearing” and “hydraulic bearing” that creality stocks both tend to have the problem you described, partly because of the orientation of the fan. Apparently with those types of bearing, the fan will not last very long when in that upright position.
For a couple of dollars more, you can get “double ball bearing” fan which will last way longer, and push more air. The one disadvantage is that the double ball bearing fan is slightly louder. You can find them on the usual websites.

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When this happens with my printers, it is usually a gap between the PTFE tube and the nozzle, or the nozzle is loose when hot. To fix this, I heat-tightened the nozzle at 200C, leaving a 0.5mm gap between the nozzle and the heater block to ensure that the nozzle was tightened against the heat break. Then, I cut 5mm of the PTFE tube and insert it into the hot end, making sure it is all the way to the nozzle.