Anet A8 Extruder Fan always ON

Hi all,

Had my A8 for about 4 years now, after many upgrades to the frame and stuff I decided to upgrade to Marlin 2.0.9.3. Everything is working fine apart from the extruder fan which is always ON from power up. The fan continues to stay on during prints. Is there anyway I can turn this off until a print job is started. I've found #define E0_AUTO_FAN_PIN -1 (attached Image) and the temp settings, but I'm struggling to work out what I should change it to. Any help appreciated

BuckRambo

I see a #define FAN_PIN 4 in the pins file. If there ISN'T a part cooling fan, then try setting E0_AUTO_FAN_PIN to 4.

Thanks, I'll give this a try tomorrow.

Thanks again

I had the same issue with the SKR_2 board and an A8.

The solution was; For the Skr_2 to be sure the part cooling fan is in the default socket (fan 0)(PB7) This socket is usually software controllable.

Next the heat break fan was installed in the (Fan1)(PB6)

These lines were commented in, in marlin 2.0.9.3

#define E0_AUTO_FAN_PIN PB6
#define EXTRUDER_AUTO_FAN_TEMPERATURE 100
#define EXTRUDER_AUTO_FAN_SPEED 255 // 255 == full speed n

100C seems to work good for the stock extruder of the A8

Thanks, looks like it's working. Fan only runs now when extruder is heating up and is over 100c

Hi!

Its been a few years since this topic, but I'm wondering what the solution was for you as the suggestion mentions a different board from the stock Anet board?

My pins config file only mentions one fan, on Pin4 which is my part cooling fan. Did you manage to get two separate fans working, or just used pin4?

Thanks

@dewr

The stock Anet board




Has 3 MOSFETS

#define HEATER_0_PIN 13 // (extruder)
#define HEATER_BED_PIN 12 // (bed)
#define FAN0_PIN 4 // (part cooling fan)

These are the only higher voltage things that are firmware controllable.

The extruder fan is normally connected directly to power, so is always on.

To make the extruder fan firmware controllable you need to add a MOSFET and tell the firmware what io pin the MOSFET is wired to with
#define E0_AUTO_FAN_PIN {IO pin you used}


You cannot set E0_AUTO_FAN0_PIN to 4 or FAN0_PIN (while FAN0_PIN is set to 4) as they are not compatible.
The part cooling fan needs to be turned on and off via gcode controll, while the extruder fan is just on when hotend is > 50 Celsius.

Note in older firmware part cooling fan is FAN_PIN, in more modern code its FAN0_PIN

Edited 2 time(s). Last edit at 04/23/2025 07:57AM by Dust.