Hello, and first of all thank you for your answer!
In fact, that’s exactly how it is, in my Marlin FW I use the PWM fan for control. So everything is clear up to this point.
But what should I do exactly?
Do you have any details? Compiling is not a problem, but I did not find any such settings in the firmware.
Could that be what you mean?
// Set number of user-controlled fans. Disable to use all board-defined fans.
// :[1,2,3,4,5,6,7,8]
//#define NUM_M106_FANS 1
// Increase the FAN PWM frequency. Removes the PWM noise but increases heating in the FET/Arduino
//#define FAST_PWM_FAN
// Use software PWM to drive the fan, as for the heaters. This uses a very low frequency
// which is not as annoying as with the hardware PWM. On the other hand, if this frequency
// is too low, you should also increment SOFT_PWM_SCALE.
//#define FAN_SOFT_PWM
// Incrementing this by 1 will double the software PWM frequency,
// affecting heaters, and the fan if FAN_SOFT_PWM is enabled.
// However, control resolution will be halved for each increment;
// at zero value, there are 128 effective control positions.
// :[0,1,2,3,4,5,6,7]
#define SOFT_PWM_SCALE 0
// If SOFT_PWM_SCALE is set to a value higher than 0, dithering can
// be used to mitigate the associated resolution loss. If enabled,
// some of the PWM cycles are stretched so on average the desired
// duty cycle is attained.
//#define SOFT_PWM_DITHER