How is heat creep characterized? I have a Delta printer with Bowden extruder and all-metal hotend. When I start printing, the hotend gets often jammed. It seems to be independent of the print I am currently doing. Retraction does not affect it either (it happened even with 0&nbsp;mm retraction).

However, despite occurring mostly at the start of the print, it also occasionally happens mid-print.

I can resolve the issue by pulling the filament out and after few seconds putting it back in only for it to happen a couple lines afterwards.

At this point it seems to me that heat creep is most likely, in spite of having a 40x40&nbsp;mm fan blowing across the fins of the heatsink.

Is this heat creep? If not, what could be the cause?
Constant jamming sounds like heat creep. It could be that:


The fan might not be powerful enough. Get a better fan
You're printing too slowly. Try increasing the print speed.
The temp might be too hot on the hot end. Lower printing temp.
The heater might be too close to the radiator. Adjust the hot end so that there is a max amount of space between them.
The firmware could be letting the hot end get too hot. With the cooling fan on, do a PID tune.
The filament might be getting stuck in the throat. Try lube, especially if you are using an all metal hot end.
Heat from the bed might be affecting the cooling fan's ability to cool the hot end. Try lowing the heated bed's temp.