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3D Printer Cooling Fan Not Working (3 Causes and Easy Fixes)

Is your 3D printer cooling fan not working? It can be caused by many reasons - which you can quickly resolve, of course.

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Is your 3D printer cooling fan not working? It can be caused by many reasons – which you can quickly resolve, of course. 

A faulty fan may be caused by wrong slicer settings, issues with the G-code, and hardware problems. Fixes include modifying the slicer settings, checking the G-code, and correcting the hardware issues (loose pins, improper welding, etc.) 

Let’s delve into these causes – and fixes – below. 

1. There’s a Problem With the Slicer Settings 

It’s not always the cooling fan that bears the problem. Sometimes, it’s due to the slicer settings. The slicer works to control the fan’s rotation speed. As such, it can dictate whether the fan turns off in specific layers – or whether it turns on at a particular height. 

The good news is there are three easy fixes for fan-related slicer problems. 

Check Your Slicer if It’s Turned On or Enabled

Your printer may also show this as ‘allow cooling’ or ‘enable cooling fans.’ If you used TPU, a material that doesn’t need cooling, then you might have left the fan off. This may be the reason why the fan hadn’t turned on. 

The same goes for ABS and PETG filaments, where cooling is not recommended. Remember, leaving the fan off can be disastrous if you’re using PLA – a filament that requires cooling. 

As always, check the slicer setting religiously!  

Lower the Slicer’s Fan Height

Fans need a certain voltage to start spinning. So if the required voltage is not met in some layers, it won’t work. This is often the case if the fan is at full height. 

To remedy this situation, set your slicer to a lower height. This allows your printer to divide the voltage into the significant amounts that the fan needs.

Set the height at 0.4 mm (0.015 inches) to get your fan running. This should give the correct voltage – while ensuring excellent adhesion between the first layers. 

Set the Right Slicer Fan Speed – And Threshold

It won’t work if the regular or maximum fan speed is set at 0. If you want the cooling fan to work correctly, make sure to set the regular speed at 80%. While ABS doesn’t require cooling per se, you can keep the speed at 20-30%. 

A low rate of 10-30%, on the other hand, applies to PETG. For TPU, a rate of 40% should do the job. As for the maximum speed, the recommended rate for PLA is 100%. 

As for PETG, you can keep the max speed at half – 50%. 

Likewise, it would be best to see if the fan speed threshold is set correctly. This, after all, determines how your fan switches from maximum to regular speed. Remember to keep it at the ideal range of 5 to 30 seconds when inputting the threshold.

2. There’s an Issue With the G-Code

The G-code is the programming language that controls the numbers in your 3D printer. It covers speed, trajectory, and displacement, among many others.

In other words, it tells your machine what and how to print. 

Check Your Printer’s G-Code File

The G-code command to turn the fan on is M106 – while the order to turn it off is M107. To verify that you have the M106 code running, slice any model with your printer’s standard settings. 

Save the G-code file and open it with a word processor. Search for the code M106, which may be included in this syntax: M106 P0 S255. The P0 indicates that the fan is linked to extruder 0. If it appears as P1, then it may be why the fan isn’t running in the first place. 

If you’re using Cura, you can verify this under: Settings > Printer > Manage Printers > Machine Settings > Extruder (1 or 2) > Cooling Fan Number.

3. Your Fan’s Hardware Parts Are Faulty

If your slicer settings and G-code are in order, then it’s time for you to inspect your 3D printer’s hardware.

Common issues include:

  • Damaged/stuck cooling fan
  • Erroneous control board current
  • Loose connection pins
  • Cut/bent/strained fan cables
  • Faulty plate welds

You can check for these problems by doing the following:

Loosen the Stuck Fan

Dust and debris can start building up inside the fan with constant use. This is especially the case if you use hairspray to enhance bed adhesion. 

Apart from cleaning the sticky debris, you can prevent this from happening again by covering your fans whenever you’re using hairspray. This should help prevent the sticky residue from forming on your fan and restricting its movement. 

Use a Multimeter

The electronics in your 3D printer may prevent the control board from delivering the suitable current or voltage. Likewise, the movement of the fans may end up cutting some cables.

You can quickly check these problems with the use of a multimeter:

  1. Unplug the wires in the control box. 
  2. Unplug the fan at the top to check for continuity. 
  3. Finally, you can put the leads on the cable ends you’re testing. 

Your multimeter should emit a beeping sound if the line is faring well. If the multimeter displays an open circuit, you will need to replace the faulty wire. 

Use the Right Pins

Of course, if the connection pins are loose, your 3D printer fan won’t run. This is often seen in parts not created by your printer’s manufacturer. 

While the manufacturer’s pins may be more expensive than the generic ones, make sure to buy them. They’ll fit the parts firmly, so you don’t have to worry about your fan not running because of these. 

Solder the Welds

Like loose pins, incorrect plate soldering may cause the fan’s connections to fail. To check the plate, remove the fan label. Inspect the solder for defects, excess tin, and loose wires. 

If there are any issues, try to solder them (granted, you know how to do so.) 


If your 3D’s cooling printer fan isn’t working, then you need to check these three things:

  • Slicer setting
  • G-code
  • Fan hardware

Fixing the slicer setting and ensuring that the G-code is correct should get your fan started. As for hardware issues, fixing problems such as loose connections and faulty welds should help your fan operate normally.

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About Ben

I started 3D printing since 2013 and have learned a lot since then. Because of this I want to share my knowledge of what I have learned in the past years with the community. Currently I own 2 Bambulab X1 Carbon, Prusa SL1S and a Prusa MK3S+. Hope you learn something from my blog after my years of experience in 3D printing.