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Check to see where you have the height set for the part cooling ducts. It should be as low as possible to point directly at the tip of the nozzle. If it is higher and air is hitting the nozzle body and even the hot-end, it may be a possible cause. If you are using Kelokera's original design parts, you may want to look at my remixes as there has been a lot done to improve the cooling ducts (and base) since his last updates in September. Check this out: https://www.thingiverse.com/thing:3182917

Hero Me Gen3 - CR-10/S Ender 3/Pro/5 OEM Hot-end