Fan Maintenance
Inspection Interval: Monthly
- Check for Noise: Unusual grinding sounds usually indicate a failing bearing.
- Clean Dust: Use compressed air to clean fan blades. Dust buildup reduces airflow.
Hold the blade still while blowing compressed air at it. Spinning a fan far above its rated speed can generate enough voltage back through the motor to damage the driver.
The three fans
| Fan | What it does | Controlled by |
|---|---|---|
| Filter | Pulls chamber air through the carbon filter | Manual slider, or the automatic air quality ramp |
| Cooling | Chamber temperature | Manual, or the automatic temperature ramp |
| Extra | Whatever you wired it to | On and off from the screen, speed from extraFanSpeed |
Only the filter fan’s runtime feeds the usage counter.
Automatic modes
The filter fan ramps from 20% to 100% following whichever of PM2.5 and PM0.3 reports worse
air, and is off below both thresholds. The cooling fan ramps from 0% to 100% between
autoCoolTempMin and autoCoolTempMax. All of the thresholds are adjustable, as covered in
Configuration.
If auto mode never reaches full speed, lower the Max values. If it is too twitchy, raise the Min values.
Diagnosing a fan that will not spin
Work through it in this order:
- Is anything overriding it? A smoke alarm stops every fan, and overheating forces every fan to 100%. Check Safety Systems before suspecting hardware.
- Is it enabled in the configuration? Each fan can be switched off.
- Does it start if you nudge it? A fan that needs a push has a failed bearing.
- Does it run at 100% but not at 20%? That is normal, since most fans have a minimum duty cycle below which they stall. Nothing is broken.
- Nothing at any speed? Check the connector at the mainboard.
Noise
Rising and falling with air quality. That is automatic mode doing its job.
A rattle at one particular speed. Resonance. Slightly changing the auto thresholds so it spends less time there usually solves it, as does a foam washer at the mounting points.
A constant grinding. Bearing. Replace it, because it will not improve.
Log it instead of guessing
If you suspect a fan is not doing much, turn on logging and
plot Fan Speed against PM 2.5 across a print. If the fan ramps up and the particle count
does not come down, the problem is airflow rather than the fan. Look at a saturated filter, a
blocked duct, or a flap that is not fully opening.