Can you 3D print without a cooling fan?

By Asked 3D Content TeamPublished Last verified

Can you 3D print without a cooling fan?

Yes for ABS, ASA, PC and nylon: shipped slicer profiles run the part cooling fan off or at 10 to 20% on long layers. PLA manages without it only on simple, slow parts; otherwise bridges sag, overhangs curl and small layers melt. The hotend (heatsink) fan is a separate fan and must always run.

The number

Material PrusaSlicer 2.9.6 profile Bambu Studio generic profile
PLA 100%, always on 100%, plus the auxiliary fan at 70%
PETG 30 to 50%, always on 40%, up to 90% on layers under 30 s
ABS Off; 15% on layers under 30 s; bridges 25% 10%, up to 80% on layers under 30 s
ASA 20%, always on; bridges 30% (Prusament ASA) 10%, up to 80% on layers under 35 s
PC Off; 20% on layers under 30 s; bridges 30% (Prusament PC Blend) 10%, up to 60% on layers under 30 s
Nylon 0%; bridges 30% (Fillamentum Nylon FX256) Off; 40 to 85% on layers under 65 s

Values come from base profiles, inherited settings included: PrusaSlicer 2.9.6’s PrusaResearch.ini (Generic unless a product is named) and Bambu Studio v02.08.04.61’s Generic @base filament profiles; printer-specific variants can differ.

Why do ABS, ASA, PC and nylon need less fan than PLA?

ABS (acrylonitrile butadiene styrene) and ASA (acrylonitrile styrene acrylate) warp when cooled too hard, while PLA (polylactic acid) has to set the moment it leaves the nozzle. Polymaker calls active cooling critical for PLA, typically at 100% to stop curling and sagging.

Polymaker names excessive cooling as a cause of ABS and ASA warping, and Prusa traces ASA’s warping to the temperature gap between the model and its surroundings. The PolyLite ABS and Polymaker ASA data sheets say cooling fan OFF, closed chamber needed. PC (polycarbonate) and nylon follow the same pattern in the table: off or 10% outside short layers and bridges.

When should you turn part cooling off completely?

  • The first layers. Every profile in the table already runs 0% for the first 1 to 6 layers, for bed adhesion. Polymaker’s rule is the first 0.5 to 0.7 mm.
  • Medium and large ABS or ASA parts in an enclosure. Polymaker keeps 20 to 50% only for small features such as pins and thin walls.
  • Nylon. PrusaSlicer’s Fillamentum Nylon FX256 profile already runs 0% outside bridges.

Keep some fan on bridges. PrusaSlicer’s profiles give them 25 to 30% even for ABS, ASA, PC and nylon.

What happens if you print PLA with no fan?

Anything printed over air, or in a layer that finishes fast, stays soft too long:

  • Bridges sag. Prusa’s bridging guide says the fans must cool the plastic mid-air for a bridge to hold.
  • Overhangs curl and droop. The edge printed over air stays soft (why overhangs droop).
  • Small parts and tips melt. The next layer arrives before the last has set (small prints melting).
A PLA bridge between two printed pillars, its strands sagging in the middle below the straight line the bridge should followWith no fan, bridge strands stay soft in mid-air and sag between the pillars instead of spanning straight.3Printed pillar1Where the bridge should be2Strands sag with no fan
  1. Where the bridge should be
  2. Strands sag with no fan
  3. Printed pillar
With no fan, bridge strands stay soft in mid-air and sag between the pillars instead of spanning straight.

If your part fan has failed and you must print, pick parts without bridges or steep overhangs. In Bambu Studio, tick Slow printing down for better layer cooling and raise Layer time on the Max fan speed threshold line above the 8 s that Generic PLA ships with. The printer then slows any layer that would finish faster. Printing several copies at once also gives each layer longer to cool.

Can you print without the hotend fan?

No. That fan cools the heatsink so filament stays solid above the melt zone. Without it you get heat creep and a jam. Firmware runs it, not the slicer: Marlin switches its extruder auto fan on above 50 °C, and Klipper’s heater_fan stays on until the hotend drops below 50 °C. See what the part cooling fan does for how the two fans differ, and the Bambu “hotend cooling fan speed abnormal” error if that fan faults.

How do you turn off the part cooling fan in Bambu Studio?

Open the filament’s settings (the edit icon beside the filament) and go to the Cooling tab. In v02.08.04.61:

  1. Under Part cooling fan, set Fan speed to 0% on both the Min fan speed threshold and Max fan speed threshold lines.
  2. Untick Force cooling for overhang and bridge, or set Fan speed for overhang to 0%.
  3. Under Auxiliary part cooling fan, set ramp up to on the Linear ramp up line to 0%. The ABS, ASA, PC and nylon profiles already leave it at 0%.
  4. Save it as a new filament preset.

For the first layers only, use Initial layer fan: For the first N layers at Fan speed 0%. The Exhaust fan group below is the chamber exhaust, not part cooling.

How do you disable the part cooling fan in OrcaSlicer?

Same place (Filament settings > Cooling), with OrcaSlicer v2.4.2’s names:

  1. Under Part cooling fan, set Fan speed to 0% on the Min fan speed threshold and Max fan speed threshold lines.
  2. Untick Force cooling for overhangs and bridges. That also covers Internal bridges fan speed at its default of -1. Leave Support interface fan speed and Ironing fan speed at their default of -1.
  3. Under Auxiliary part cooling fan, set Fan speed to 0%.

For the first layers only, set No cooling for the first N layers under Cooling for specific layer. It stops every part cooling fan for those layers.

Can you turn the fan off with G-code?

Yes. M107 switches off the print cooling fan in Marlin and Klipper, and M107 P<index> picks another fan in Marlin. It lasts only until the next fan change in the file: Bambu Studio, OrcaSlicer and PrusaSlicer write a new M106 whenever their computed fan speed changes. To keep the fan off for a whole print, set it in the slicer.

How to check it on your own print

  • Slice and switch the preview to Fan Speed in Bambu Studio or OrcaSlicer. With the fan off, every layer reads 0, bridges included.
  • Print a short bridge test first. If it sags, give bridges back 25 to 30%, the PrusaSlicer profile value.
  • On ABS or ASA, look at the walls. Lifting corners or split layers mean the fan is still too high or the enclosure is open (ABS fan speed).

Sources

  1. resources/profiles/PrusaResearch.ini at version_2.9.6, PrusaSlicer on GitHub (accessed October 24, 2026)
  2. src/libslic3r/GCode/CoolingBuffer.cpp at version_2.9.6, PrusaSlicer on GitHub (accessed October 24, 2026)
  3. BBL filament profiles at v02.08.04.61 (fdm_filament_common, pla, pet, abs, asa, pc, pa; Generic PLA, PETG, ABS, ASA, PC, PA @base), Bambu Studio on GitHub (accessed October 24, 2026)
  4. src/libslic3r/PrintConfig.cpp at v02.08.04.61, Bambu Studio on GitHub (accessed October 24, 2026)
  5. src/slic3r/GUI/Tab.cpp at v02.08.04.61, Bambu Studio on GitHub (accessed October 24, 2026)
  6. src/libslic3r/GCode/GCodeEditor.cpp at v02.08.04.61, Bambu Studio on GitHub (accessed October 24, 2026)
  7. src/libslic3r/PrintConfig.cpp at v2.4.2, OrcaSlicer on GitHub (accessed October 24, 2026)
  8. src/slic3r/GUI/Tab.cpp at v2.4.2, OrcaSlicer on GitHub (accessed October 24, 2026)
  9. src/libslic3r/GCode/CoolingBuffer.cpp at v2.4.2, OrcaSlicer on GitHub (accessed October 24, 2026)
  10. M107: Fan Off, Marlin Firmware documentation (accessed October 24, 2026)
  11. Marlin/Configuration_adv.h at 2.1.2.9 (EXTRUDER_AUTO_FAN_TEMPERATURE), Marlin on GitHub (accessed October 24, 2026)
  12. docs/Config_Reference.md at v0.13.0 ([heater_fan]), Klipper on GitHub (accessed October 24, 2026)
  13. docs/G-Codes.md at v0.13.0, Klipper on GitHub (accessed October 24, 2026)
  14. Cooling, Polymaker Wiki (accessed October 24, 2026)
  15. PolyLite ABS Technical Data Sheet, Polymaker Wiki (accessed October 24, 2026)
  16. Polymaker ASA Technical Data Sheet, Polymaker Wiki (accessed October 24, 2026)
  17. ASA, Prusa Knowledge Base (accessed October 24, 2026)
  18. Poor bridging, Prusa Knowledge Base (accessed October 24, 2026)