Fan 2 always on

I just switched my Workhorse printhead to the M175 head, and the fan 2 that blows on the extruder is always on, even when there is no print going, and it’s somewhat loud. It comes on before the Marlin splash screen is even off. I go to Temperature>Fan Speed 2 and set it to zero, or any value, but it does not change. Is this normal?

This fan is always on by design. The part cooling fan is controlled by M106 and M107.

I’m not sure what Fan 2 is on the Workhorse as I only have Fan 1 on my TAZ 6.

Surely not. Why would that fan come on even when there’s no printing to be done? It’s so loud. I’m putting these print heads on a Workhorse and two of my Mini 2s for my classroom, and I don’t think I’m going to be able to handle this level of noise.

I believe it is pretty much standard practice for the cold end fan to be always on. You can ask

I just checked my M175 tool head and I agree that the 25mm cold end fan is pretty loud. All my other tool heads have 40mm fans which are much quieter.

I have a smart plug attached to my TAZ 6 so I can turn the printer off when there’s no printing to be done. When printing, the sound from the stepper motors drowns out the cold end fan.

I also have a Raspberry Pi connected to my TAZ 6 running OctoPrint. I have a plugin for the smart plug that can optionally turn the printer on when a file is uploaded and turn the printer off when it is idle.

I’m not sure if the 5v pins that the Rambo board uses for heatbreak fans is constant or can be switched. If it is controllable over firmware, you can configure Marlin to only power the heatbreak fans when the nozzle is at or above a certain temperature.

But the fan should be nearly silent, so if it’s noisy enough to be an issue, it may need replacement.

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The fan is NOT nearly silent. It’s all air noise, like a loud server fan, though, so I doubt it’s defective. I notice that the fans on the stock printheads run all the time as well, but they are larger fans and don’t make much noise. I notice that the fans on my Prusa printers turn off when no print is running, and they run Marlin, so it should be possible. My Prusa printers cost $750 while the Workhorse costs 4x as much, so surely the control board is at least as good as the Prusa’s.

Hello Brian,

The small fan is a bit noisy, yes. Small fans generally are.

Having the fan turn on and off is definitely something we can look into as a feature.
If you have any suggestions or issues you are seeing, you can submit those to our GitLab page linked below via the “New Issue” button.

The 5v fan is plugged into a 5v aux port, so it is always powered when the board has power. There are a few ways to accomplish it if you dig into the schematics of the Rambo and identify open and assignable pins that can supply 5v power. One way is to change the heatbreak fan to 24v, modify pins.h to reassign the hot end 1 part cooling fan to be used as the hot end 0 heatbreak cooling pins, recompile marlin with the heat-initiated heatbreak fan options and temps… and you should be able to have variable speed and on/off control. (image is from Taz6 pins, since workhorse diagram doesn’t show the second fan connection)