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Crypto Miners Direct

Maintenance guide

ASIC Fan Replacement

Recognise a failing ASIC miner fan, confirm the fan is the fault, choose a matching replacement and fit it safely with the right checks afterwards.

Published October 1, 2026 · Reviewed by James Emerson

A failing fan shows up as a missing fan, a speed reading that is zero, far too low or impossibly high, or as noise and vibration. Before buying a part, confirm the fan is at fault by moving it to another fan port or trying a known-good fan in its place. The replacement must match the original in size, voltage, current rating, connector and pin count, and it must be fitted to blow the same way. The manual for your exact model is the authority on disassembly, and opening a machine can affect warranty.

Key points

  • Air-cooled miners stop or slow down when a fan is missing or too slow. This is a protection; fix the fan, do not work around it.
  • Swap-test before you buy. If a good fan in the same position still reads wrong, the fault is the cable or the control board.
  • If every fan reads zero at once, suspect the fan power supply, not four fans.
  • Match the label on the old fan: size, voltage, current, connector and number of wires.
  • Power off and unplug before opening anything, and discharge static before touching fan connectors.

Symptoms of a failing fan

Bitmain's fan troubleshooting articles for Antminers describe these cases, and the same logic applies to other air-cooled miners:

Symptom Likely cause First action
Fan missing from the status page, or speed 0 Loose or damaged fan cable, failed fan, or damaged fan port on the control board Reseat the connector, inspect the cable, then swap-test the fan
Speed too low Worn fan or poor connection Reseat, then swap-test
One fan much slower than the others, no error yet Fan starting to fail Replace it before it stops
Speed reading impossibly high Fault inside the fan's speed signal. Bitmain treats readings above 10,000 rpm as a damaged fan Replace the fan
All fans read 0 Usually the 12 V supply to the control board, not the fans Reseat the control board power cable, test the power supply
Noise, vibration, blades touching the grille Broken blade, worn bearing or bent grille Replace immediately

Bitmain notes that a vibrating fan damages the miner over time, and that a damaged fan cable can short against the chassis, so physical damage is a reason to replace even if the speed looks normal.

What the log says

On Antminers the kernel log names the fault. Bitmain documents these messages:

  • Fatal Error: some Fan lost or Fan speed low! in its general fan troubleshooting article.
  • ERROR_FAN_LOST for 19-series models when a fan is lost or its speed is low.
  • Sweep error string = F:1 for the S19 XP, meaning a fan is abnormal, with zero speed or a speed clearly different from the others.

Other models and other manufacturers use different messages. MicroBT refers WhatsMiner owners to the error codes shown in WhatsMinerTool and its operation guide. Use the documentation for your model and do not assume a code means the same thing elsewhere.

Fan, cable, control board or power supply

Work from the cheapest explanation to the most expensive, with the machine powered off and unplugged for every change.

  1. Reseat the connector. Check the fan plug is fully home in its socket and that the cable and any extension lead are not cut, pinched or scorched.
  2. Swap-test. Move the suspect fan to a port where a fan is reading normally, and put that good fan on the suspect port. If the fault follows the fan, replace the fan. If the fault stays with the port, the fan is fine.
  3. Port fault. Bitmain's guidance is that if the problem remains after fitting a good fan, the control board is damaged and needs replacing or repair. See Control Board Replacement.
  4. All fans dead. Bitmain attributes this to an abnormal 12 V supply: reseat the 12 V cable or test with another power supply.

Identifying the correct replacement

Read the label on the hub of the old fan and match every item.

Attribute Where to find it Why it matters
Frame size Label or measure. Written as width and depth, for example 12038 means 120 × 120 × 38 mm It must fit the mounting holes and shroud
Voltage Label, in V DC A fan of the wrong voltage will not run correctly and may be damaged
Current or power Label, in A or W Indicates how powerful the fan is. A weaker fan moves less air; a much stronger one may overload the fan circuit
Rated speed Label or manufacturer documentation Firmware expects speeds in a certain range
Wire count and connector Count the wires and compare the plug Must mate with the control board socket without force
Airflow direction Arrow moulded on the frame Intake and exhaust fans must both blow front to back
Position Intake or exhaust, and which fan number Some models use different fans front and rear

For Antminers, Bitmain's fan article describes a standard 12038 four-wire fan, and says that 17 and 19 series fans run at 6,000 rpm, with some rear fans at 4,800 rpm that can be replaced by 6,000 rpm units. The four wires carry speed control (PWM), the speed signal back to the control board, power and ground. MicroBT's air-cooling guide describes a 4-pin fan cable on WhatsMiner models. Newer models may differ, so check the old fan's label and the model's manual, not the family name.

A fan that fits mechanically but has a different connector or wire order is not a match. Do not re-pin or splice a connector on the basis of a guess; a wrong connection can damage the control board. Bitmain warns that fan connectors link directly to IC pins.

Fans are listed under cooling fans. On warranty: Bitmain states that replacing a fan does not affect the miner's warranty, and that fans supplied on their own as spares carry no warranty. MicroBT's warranty policy excludes damage caused by unofficial accessories, naming fans, and by disassembly without its authorisation. Check the terms for your machine.

General replacement procedure

The steps below are the general sequence. Screw positions, covers and cable routing vary by model, so follow the manufacturer's procedure for yours. Bitmain publishes one for its integrated-PSU Antminers, summarised after the list.

  1. Shut the miner down, switch off the supply and unplug the power cords. Wait for the fans to stop.
  2. Disconnect the network cable and move the machine to a clean bench.
  3. Discharge static with a wrist strap or by touching grounded bare metal.
  4. Photograph the fan's orientation, connector position and cable routing.
  5. Remove whichever covers give access to the fan connector on the control board.
  6. Unplug the fan connector by its housing, not by the wires.
  7. Free the cable from ties and guides.
  8. Remove the fan's mounting screws while supporting the fan and grille.
  9. Fit the new fan with the airflow arrow pointing the same way as the old one. Refit the grille and tighten the screws evenly. Do not overtighten into plastic frames.
  10. Route the cable as before, clear of the blades and of hot or sharp parts, and secure it.
  11. Plug the connector into the same socket. It should seat without force.
  12. Refit the covers.

Bitmain's procedure for integrated-PSU Antminers adds these model-specific points: the machine has four fans, numbered on the control board to match the status page, with FAN1 and FAN2 generally at the rear and FAN3 and FAN4 at the front; the control board cover is removed first, and the power supply cover as well for rear fans; the fan cable tie and protective tape are removed; a rear fan's cable passes under the power supply copper bar, which does not need to be removed; each fan is held by four screws; and the fan must be installed so that air flows from front to back.

Post-replacement checks

  1. Spin the new fan by hand before powering on. It should turn freely with nothing touching.
  2. Power on and watch the start-up. All fans should spin.
  3. In the web interface, confirm the expected number of fans is detected and that each shows a plausible speed, similar to its pair.
  4. Check the log for fan errors.
  5. Feel for airflow at the exhaust and confirm it leaves from the rear.
  6. After an hour, compare board temperatures and average hashrate with the machine's records.

Record the date, the fan position and the part fitted.

When to stop and use a repair service

  • The fault stays on the same port with a known-good fan. That points to the control board.
  • The connector or socket is scorched, melted or has bent pins.
  • You cannot find a fan with a matching connector and rating.
  • The machine overheated before the fan fault was found and now reports missing chips or boards.

In those cases open a repair ticket with the manufacturer or use a qualified repair centre. Bitmain notes that for a miner under warranty, a free fan replacement requires returning the whole miner, not the fan alone.

Sources