Thermal runaway and nozzle temp too low

Two errors ive been getting recently.

I find when i turn my fans off, i can get 215 degrees without an issue. When the fans are on, the hot end really struggles to get up to temp and then shouts one of those two errors at me and beeps like crazy until i switch it off.

Would a firmware update help? I have stock firmware, ender 3 v2. Are the fans all that necessary anyway or can i just leave them off?

The main fan (the 1 facing the front; the blade fan rather than squirrel) is normally needed, in order to cool the heat break of the hotend, so you don’t get heat creep.

So what should i do? When the fan is on it struggles to reach temp, ultimately giving me one of those errors. Im trying to update the firmware now, but im having trouble with that because its a linux machine and i dont know linux very well.

Im full of problems today lol

Is it possible the fan is aimed incorrectly; that it’s hitting the heat block rather than the cooling block?

Oh wow i didnt think of that. I wouldnt even begin to know how to fix that. Do i just tilt the fan up inside the housing?

Check your electrical connections for the heater cartridge (with the power off and printer unplugged!). I had a a printer throw errors and not reach temperature or die shortly after a print started. I replaced the hotend with a spare thinking it was the heater cartridge but the error came back. Turns out a pin in the connector to the hotend from the motherboard was bad.


Check if the thermistor is mounted and fixated deep inside the heater block.

If it is not all the way in the air flow from the part cooling fan will stream over it and lowers the temperature of the sensor, which is not what you want :smiley: Also make sure the hotend parts are not moving when the block is heated up. you need to tighten the screws on the heater block, which are holding the sensor and the heater cartridge when the block is hot, due to thermal expansion. If you screw stuff into the cold hotend and heat it up, everything gets loose again. Especially the heater cartridge likes to slide out, when the locking screw gets loose in hot condition and the part outside is catching fresh air quite easy.

Been super busy with work but finally got around to it and Geit nailed it. My heater element was hanging out of the block some. I seated it deeper in there and it fixed my thermal problem THANK YOU GEIT!!

Now time to work on my extrusion problems…ill make a new post in a bit.

Well spoke too soon.

If my fans are on, my hot end struggles badly to reach and maintain 210.

If i turn my fans off, i risk heat creep.

My fans also sound terrible. This printer isnt that old, so whats going on?

There have been quite a few posts about how the fans on the Ender 3 V2 in particular are crappy & die after a few weeks to months.

Can i replace the fans? Would that help?

Im seriously at a loss here and cant get help on reddit or anywhere.

Certainly the fans can be replaced. You need to be comfortable with basic electronic work: soldering, cutting, stripping of wire, etc. You can get fans on Amazon. Just search for “24v 40mm fan”. The normal 3D printer cooling block fans are 40x40x10mm.

And if ive never done that electrical work before?

Jeez i just want my printer to work again ??

Then you need to learn how, get someone to do it for you or, if it’s under warranty, complain to the company you bought it from.

This is exactly why I suggest to get a printer kit as first printer, so you learn how it works and how to fix things. A 3D printer is not a micro wave. It is a device that will fail far earlier and need maintenance. This is way ready to run commercial printers are so expensive. They calculate the warranty and support into the pricing.

So no one here knows why i cant maintain temp on my machine? Why do the fans being on not allow my machine to maintain 215?

But perhaps a ready-to-run commercial printer is what he needs/wants. It might be worth it to him.

I’m not very familiar with the Creality lineup, but you have 3 fans on the hotend assembly–right? Two part cooling fans and a fan for the heat sink. Only the heat sink fan should be on when the hotend is heating up. If the printer is under warranty, return it for a replacement. If not, buy a new or a replacement hotend (keep the original) as the simplest solution.

It might also help to see some picture and maybe video of your hotend in the off chance it was assembled incorrectly at the factory.


@Alan, most Creality printers have 2 fans: an axial fan for the cooling block and an squirrel cage type for part cooling.

Have you tried a silicone sock for your heater block? They help maintain block temperatures and insulate them from the thermal shock of part cooling fans turning on and off. The tip to check your cooling fan duct alignment was a good one, as you want to reduce cool air blowing on the block (makes sense), but some is inevitable. A silicone sock helps. If your printer had the cheap cloth type insulating material or a silicone one fell off, replacement is definitely recommended. You might also look into a better cooling duct design.