The A1 Mini is really noisy and this is because Bambu Lab installed the Hotend fan from the X1 series as mainboard fan. It is only 15x15x10 mm in size and runs with up to 15.000 rpm. To make the A1 Mini a silent printer for office use, i developed this fan mod.

I made this external case to house a 40x40x10 mm Noctua 5V PWM fan (Noctua NF-A4x10 5V PWM). It can be used as addition to the original mainboard fan for better cooling or as replacement of the original Bambu Lab 15x15x10 mm fan that is way too noisy for me.

Option 1:

For use as additional fan for better cooling, just print my case, install any 40x40x10mm fan in it and attach the case to the printer. You may want to fix the case with double duct tape. You can power the fan with a USB-Charger.

Option 2:

Open the A1 Mini case (follow Bambu Lab Wiki for A1 Mini fan replacement), remove the noisy Bambu Lab Mainboard fan and close the case (without original fan). Store the original fan for later use and attach my external case with any 40x40x10 mm fan in it. Power it with any USB-Charger.

By removing the original fan, the printer gets more silent but its not perfect because the new external fan will run without PWM control with 100% speed. Its better than the original but not perfect.

Option 3 (best result):

1. Open the A1 Mini case (follow Bambu Lab Wiki for A1 Mini fan replacement) and remove the noisy Bambu Lab Mainboard fan. Install the Noctua NF-A4x10 5V PWM or any 40x40x10 mm 5V fan in my external case. Note: do NOT use a 12V fan ! You need a 5V fan because we will connect it to the original fan header on the A1 Mini mainboard.

2. Cut the fan cable (try to get a maximum cable length) and lead the cable through one breathing hole of the A1 Mini case.

3. Cut the plug from the original fan. Note that this is the Bambu Lab Hotend fan for X1 series so you can buy a new one easily in case you want to set the fan to default later. Try to get as long cable length as possible. Note: this will destroy the original fan so you need to buy it if you want to reset the fan mod later.

4. Connect the plug cables with the fan cables. Note that Bambu Lab uses standard PWM polarity but different colors for the cables. I made a drawing with correct mapping for the Noctua fan (which uses standard PWM polarity):

You can solder the cables and than isolate them or if you bought the Noctua fan, 4x Noctua Omnijoin adapters are supplied in the package. You can press together the Noctua Omnijoin Adapter with a flat pliers. If you use the Noctua Omnijoin adapters, the cables do not need to be stripped.

Polarity is:

Plug dark gray → Fan black (- / GND)

Plug black → Fan yellow (+ 5V)

Plug gray → Fan green (RPM)

Plug white → Fan blue (PWM)

My connection (not using the Noctua Omnijoin adapters but i recommend you to use them as its easier).

5. Connect the Plug to the mainboard as it was before.

6. Close the A1 Mini case.

7. Enjoy a much more silent A1 Mini. The PWM control of the fan works fine with the Bambu Lab PWM control.

Note: by using this fan mod, you may brake your A1 mini and void your warranty. Use absolutely at your own risk !