Side fans stopped working

I had started a different thread about my filament getting chewed up, eliminating different things brought me to this… It turns out that my side fans (Taz 6, default single print head) are not starting. The console command to turn them on does not work. So what are the steps to troubleshoot this?


What’s the console command you are using to turn on the fans? Have you tried using the controls in the LCD panel?

With a cheap voltmeter you can check if 24v is present on the fan connectors(pins 7 & 8) when the fans are supposed to be on. See illustration in section 11 here:

Thanks for the reply Joe,

I use M106 to attempt to start the fans and nothing happens (cables connected, everything on, etc). I would like to know a console command I could use to test just to make sure that console commands work if you have any suggestions (like move the z axis up 5 mm or something) that would be great. As for testing for power, I’ve never used a multi meter though I was planning on picking one up after I move (on the 31st) but I’d rather resolve this asap so I’ll order one today. Might take a day or two to get it though. I assume that the diagram you’re talking about is the one I’ve attached.

Also I looked around on the LCD panel menus and I can’t find anything to turn on the side fans. Could you give me a walk though on the menus to get there?

Additionally I noted that I am using Cura Lulzbot Edition 3.6.21 (and associated firmware) and the site mentions that that is an experimental version. and 3.6.20 is the latest stable version. I just found the link to download 3.6.20. I’ll give downgrading a go and let you know how that works for me.

So let me know if the diagram of the connector is the right one, I’ll get a multi meter in a day or two, let me know about the menus when you get a chance.


PS Using the printer is the way I unwind. Having it down is a source of constant stress (dramatic but true).

Update: I downgraded the firmware to the version installed by Cura Lulzbot Edition 3.6.20 and now the console command for starting the side fans work. I’m going to try a print right now! I’ll post an update in a few hours.

Best Regards,


Well heck. It looks like the filament’s stuck in the print head. I turned the heat up so it would slide out but I guess the filament is too high up in the print head for that to work. Guess I’ll be disassembling the print head tonight. I’ll keep you apprised of my progress.


You can usually clear those jams by covering the hotend fan and setting the hotend to 230. Gently tug on the filament while the hotend warms up. It will usually release when the cool section of the hotend gets warm due to the lack of cooling caused by the blocked fan.

Yes that is the correct diagram! To use the console commands you must have the usb cable connected to the printer and computer (I assume you do). Start Cura, click on the Monitor tab, Under the Manual Control section click on the Connect button, then click on the Console button. The Console screen will appear. To move the z-axis upward 25mm enter G0 Z25 Move it back down in the opposite direction simply make the number negative G0 Z-25. To move the X or Y axis simply replace the letter Z with the letter X or the letter Y.

To view your Z offset enter M851
Send all your axis to their home positions type G28

Looks like typing M106 only would turn on your heat sink cooling fan. If no fan index is given, the print cooling fan is selected. There’s 3 fans so you need to pass the index value of the fan you’re trying to turn on. I assume 0, 1 or 2 would be the index numbers (preceded by the letter §). So try M106 P1. See if one of the side fan comes on at full speed (full speed of 255 is default if the speed value is not specified (with the letter S)). Then type M107 to turn the fan off. Turn the fan on at approx. half speed M106 P1 S128. You can read about the fan speed and other Gcode commands here:

I don’t know 100% the steps to tell you how to test the fans through the LCD panel but it shouldn’t be too hard to scroll through the few menus and find it. Currently I have the Aerostruder print head installed and there’s only one fan on it. To turn the fan on I need to go to Temperature -> Fan Speed 1: and turn the knob to the fan speed I want (0-255). Yours should be somewhat similar to that.

Know that a lot of times the side cooling fans don’t turn on for the first layer to allow for better adhesion to the build plate. So its possible that your side cooling fans not working assessment may be incorrect; but its fun to learn these commands anyways. :slight_smile: