Creality Ender 3 Fan

There is no single “Ender 3 fan” — and that is where most fan advice goes wrong. An Ender 3 has three different fans doing three unrelated jobs: one keeps the hotend’s cold side cold, one cools the plastic just printed, and others keep the electronics alive. The older version of this page made the confusion worse by inventing a “print bed fan” — no such fan exists; nothing blows on the bed, which is heated, not fan-cooled. Separate the three real fans, and every fan problem on this printer gets easier to read.

The three fans, and what each one actually does

1. The hotend (heat-sink) fan — the one that must never stop

This fan blows across the heat sink, the finned section above the heater block. Its job: keep everything above the nozzle cold, so filament only melts in the melt zone. On a stock Ender 3 it is wired to run whenever the printer is powered on (later boards may tie it to hotend temperature instead — either way, not under your control, and not meant to be).

The rule is absolute: if the hotend is hot, this fan must be spinning. If it slows or stops, heat creeps up the heat break, filament softens and swells where it should still be solid, and the printer jams.

2. The part-cooling fan — the one your slicer controls

This blower points down at the nozzle tip through a duct. It cools the plastic, not the machine: freshly laid filament is soft, and a controlled blast of air sets it before the next layer lands on it. It is the only fan your slicer commands, and the only one you can adjust from the printer’s screen mid-print.

On a stock machine the duct blows from one side only, which is why overhangs facing away from the duct look worse than overhangs facing it — a limit of the design, not a fault.

3. The mainboard and PSU fans — the ones you forget until they grind

Inside the electronics case, a fan cools the mainboard’s stepper drivers; the power supply has its own internal fan, mostly noticed as background noise. They matter, though: a dead board fan lets the drivers overheat on long prints, which shows up as sudden layer shifts or missed steps hours into a job — symptoms people rarely connect to a fan. The PSU fan sits inside a mains-voltage enclosure — if it fails, replace the power supply rather than opening it.

Where they sit: on the original Ender 3 and the Pro, the hotend fan and part-cooling blower sit side by side in the fan shroud on the print head — an axial fan for the heat sink, a radial blower for part cooling. The V2 uses a restyled shroud around the same arrangement, and its board-fan behaviour differs between board revisions, so treat exact V2 wiring as model-specific.

Part-cooling fan settings, by material

The part-cooling fan is the only one you set — and what matters is how much air each plastic wants after the first layer. The first layer is always printed with the fan off, because cooling it would fight bed adhesion (our CR-10 bed adhesion guide covers that fight in full).

Material	Part-cooling fan	Why
PLA	100% from layer 2–3 onwards	PLA stays soft for a long time; full cooling gives crisp overhangs, clean bridges and sharp detail
PETG	0–50% (lower for strength, higher for detail)	Layers bond best warm; full fan weakens adhesion and can leave prints brittle, though some fan sharpens details
ABS / ASA	Off, or minimal (up to ~20–30% for tiny parts)	They shrink as they cool; blasting them invites warping and split layers — they want an enclosure, not airflow
TPU	Low, roughly 0–40%	Needs some cooling for overhangs, but too much air adds stringing and weak bonding

These are starting points: big overhangs want more air than a chunky functional part in the same filament, and minimum-layer-time settings change fan behaviour on small layers.

What a failing fan looks like

Each fan fails in its own recognisable way:

• Hotend fan dying: prints start perfectly, then clog or under-extrude part-way in — often around 20–40 minutes into the job, every time. The extruder starts clicking, the nozzle jams, and a cold pull reveals a swollen plug of filament. That time-delayed pattern is the classic signature of heat creep from a weak or stopped hotend fan.
• Part-cooling fan failing: overhangs sag and curl, bridges droop, and small details look melted — worst on the side of the print away from the duct, and worse on PLA than on anything else. The print finishes, but one side looks drunk.
• Board fan failing: nothing at first, then layer shifts or skipped steps deep into long prints as the drivers cook — recovering once the machine cools.
• Any fan getting noisy: a rising whine, rattle or grinding that comes and goes is usually a worn bearing. The cheap sleeve-bearing fans fitted to these machines are a wear item: noise is the early warning, seizure the end state.

Troubleshooting: fan, wiring, or board?

Work through it in this order before buying anything:

1. Watch and listen at power-on. The hotend fan should start with the machine. With power off, spin each fan gently by hand — gritty, stiff or wobbling means it is mechanically finished.
2. Check for obstruction. Pet hair, filament wisps and dust stop small fans more often than electronics do. Clear the blades and the duct.
3. Check the connectors. The little JST plugs work loose, and the thin wires fatigue where they flex with the print head. Reseat the connector, and flex the cable gently while the fan runs, listening for dropouts. Power down before unplugging anything on the board.
4. Swap-test. The hotend and part-cooling fans use the same connector style, so plug a suspect fan into the other fan’s output (power off while swapping). If the fault follows the fan, the fan is dead; if it stays with the output, the problem is wiring or the board.
5. Measure, if you have a multimeter. A stock Ender 3 is a 24 V machine, so a live fan output should read about 24 V. An output reading nothing with the fan commanded on points at the board; full voltage at a silent, unobstructed fan confirms the fan.

Replacing a fan: the 24 V rule

Replacements are where Ender 3 owners most often go wrong, so one rule first: every stock Ender 3 fan is a 24 V fan, because the whole machine is a 24 V system. Match three things on any replacement: voltage (24 V), size (the hotend pair are 40 × 40 mm class — measure the old fan rather than assuming), and connector.

The trap is quiet fans. The popular silent replacements, Noctua being the famous example, are 12 V fans. Wired straight into a 24 V Ender 3 they will burn out. They need a buck converter (a small step-down regulator) wired in line and set to 12 V. And there is a second, honest trade-off: small Noctua fans move noticeably less air than the stock 24 V fans. On part cooling that is usually acceptable; on the hotend fan it is a real risk, because reduced heat-sink airflow is exactly what causes heat creep and mid-print clogs. Plenty of people run them happily; plenty of “mystery clog” threads end with one. Keep the stock fan so you can swap back and test.

A like-for-like 24 V fan with ball or hydraulic bearings will outlast the sleeve-bearing originals, and usually runs quieter doing it.

Frequently asked questions

Should the Ender 3’s hotend fan run all the time?

Yes. On a stock machine it runs whenever the printer is powered (some later boards switch it with hotend temperature instead). It is not slicer-controlled and should never be turned off while the hotend is hot — it alone prevents heat creep and the clogs that follow.

Can I control the Ender 3’s fans from the slicer?

Only the part-cooling fan. Your slicer’s fan-speed settings — and the Fan Speed option on the printer’s screen during a print — command the part-cooling blower. The hotend fan and board fan are automatic. There are no panel switches for the other fans.

Why do my prints clog about half an hour in, every time?

That pattern points at the hotend fan, not the nozzle. A weak or stopped heat-sink fan lets heat creep upward until filament softens and swells inside the heat break — a process that takes about that long from a cold start. Check the hotend fan first; once it is ruled out, work through the rest of the machine with our Ender 3 calibration guide.

Can I fit a 12 V Noctua fan to my Ender 3?

Yes, but never directly: the Ender 3 is a 24 V system, so a 12 V fan needs a buck converter set to 12 V wired in line, or it burns out. Weigh the trade-off too — quiet fans move less air, which matters most on the hotend fan.

Which fan has failed if my overhangs sag on one side only?

The part-cooling fan — or its duct. Stock Ender 3 cooling blows from one side, so the far side always cools worst; if that side suddenly gets much worse, check the blower is spinning and the duct is clear before changing slicer settings.