Replace the Ultimaker 3 radial fans

The fans at the side of the print head (the radial fans) spin during printing. This ensures that the layer of filament is properly cooled down before the next layer is put on. Most materials require this extra cooling to retain optimal print quality.

If the fans are not spinning when they should be, they need to be replaced. The following steps describe how to correctly replace the model cooling fans.

Caution: Before you start, ensure the print cores have completely cooled down. Turn off the printer and disconnect the power cable.

Requirements and info


1 - 2x 2135 - Radial fan 35x35x10
1 - 2x 2158 - Foam tape 25x9x4 (optional)


2 mm hex screwdriver
Tape (optional)

Time 15 minutes
Difficulty level 3 - Medium


Ultimaker3_Loosen-side-fan-bracket.jpg Ultimaker3_Move-fan-bracket-down.jpg
1. Loosen side fan bracket 2. Move bracket down

Use the hex screwdriver to remove the four screws that hold the side fan bracket.


Slightly open the front fan bracket and move the front and side fan bracket assemblies down to create some room.




3. Disconnent the fans

4. Remove the fans

At the back of the print head, carefully disconnect the side fans from the left and right connectors of the print head PCB.


You can now take both fans out of the side fan bracket (they are not screwed into place).


Side-fan-orientation.jpg Ultimaker3_Loop-fan-wire.jpg
1. Fan orientation 2. Fan wires

Look at how the fans will be placed in the print head; the fan will face towards the inside of the print head, and the open side will face down.
Note: Reference image only, do not place the fan yet!


Loop the fan's wires at the back of the fan, taking the orientation into account. Ensure the connector comes out at the back, with ~3 cm if wire sticking out. You can secure the wire with a piece of tape.


Side-fan-foam.jpg Ultimaker3_Place-new-side-fan.jpg
3. Foam tape 4. Insert the fans

The fans are held in place with some foam tape. If this tape is on the print head header bracket, move to the next step. If it was on the fan, apply a new piece of foam tape to the top of the fan.


Slide the right fan into the right side of the fan bracket. Ensure the orientation is correct and the fan's wires come out at the back. Repeat this for the left fan.



5. Connect the fans

6. Align the bracket

Connect the fans' plugs to the connector on the corresponding side of the print head PCB. Ensure that the fans stay in the bracket while doing so and move the fans' wires behind the plastic.


Carefully move the side fan bracket upward again so you can fully close it. It should align nicely with the header bracket. At the back, check that no wires have gotten pinched.




7. Secure the bracket

8. Close front fan bracket

Insert the four screws in the holes of the header bracket. Use the 2mm hex screwdriver to tighten them. Ensure the side and header brackets stay well-aligned while securing the screws.


Finally, close the front fan bracket again. Check if it can still be closed easily and it remains firmly closed. If not, check the wires on the inside of the print head; you may have to improve the wire positions.


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