Fan Lowering Hot End Temp

I have a Taz 2.1 and I am having a problem where when the fan comes on as part of the cooling cycle, it lowers the temperature of the hot end. It was such a fluctuation in temperature that it would get to the point were the filament would not be hot enough to extrude and it would strip out the filament. A couple of months ago, I convinced my work to buy a Taz 4 which doesn’t seem to have nearly as bad of a problem with the temperature swings. I thought to myself, this must be a result of the new 24 volt system. So I ordered the 24 volt upgrade for my Taz 2.1 and got it all hooked up and reflashed the firmware, everything seem to be working (except for an occational blank screen when I turn on the machine which I also get with the Taz 4, after I turn on and off couple of times it comes on, I did’t check the cable connection) Anyway back to the upgraded Taz 2.1, it is alot better that before, but I did have a temp swing printing ABS from 230 to 193, which is very close to a failed printed I quickly sent a m106 s0 which has been my failsafe. I’m thinking also even it the print doesn’t fail, these temperature swings surely affect the layer adhesion which could be another problem people are having with layer adhesion, if a constant temperature can’t be maintained. I read another post about tweaking the PID settings, is there something that could be done to maintain a more stable hot end temperature with the fan blowing a variable speeds through out the build. I would appreciate any feedback or suggestions or anyone else noticing a similar situation.

You can limit the fan speed in Slic3r or your preferred slicing engine. The setting can be found at: Slic3r > Filament Settings > Cooling > Fan Settings > Fan Speed Max: and set it to 66%, save and regenerate your gcode file. Feel free to adjust the fan speed max percentage setting if you need a bit more cooling.

You may also want to try this fan add on instead, as it also provides cooling for the hot end heat sinks (slightly reducing the amount of air moving around the heaterblock: