Fan slowing down after first layer

I am currently using Slic3r for my 3d printer but i noticed something weird causing my printer to jam. The first layer has the fan running full speed at 255, i made slicer do this by manually putting it into the g code at the start of the print. After the first layer though the speed drops down to 136 instead of 255. I am currently using Marlin on my Kossel mini but im not quite sure what is causing this to happen.

//This is for controlling a fan to cool down the stepper drivers
64 //it will turn on when any driver is enabled
65 //and turn off after the set amount of seconds from last driver being disabled again
66 #define CONTROLLERFAN_PIN -1 //Pin used for the fan to cool controller (-1 to disable)
67 #define CONTROLLERFAN_SECS 60 //How many seconds, after all motors were disabled, the fan should run
68 #define CONTROLLERFAN_SPEED 255 // == full speed
69

70 // When first starting the main fan, run it at full speed for the
71 // given number of milliseconds. This gets the fan spinning reliably
72 // before setting a PWM value. (Does not work with software PWM for fan on Sanguinololu)
73 //#define FAN_KICKSTART_TIME 100
74

75 // Extruder cooling fans
76 // Configure fan pin outputs to automatically turn on/off when the associated
77 // extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
78 // Multiple extruders can be assigned to the same pin in which case
79 // the fan will turn on when any selected extruder is above the threshold.
80 #define EXTRUDER_0_AUTO_FAN_PIN -1
81 #define EXTRUDER_1_AUTO_FAN_PIN -1
82 #define EXTRUDER_2_AUTO_FAN_PIN -1
83 #define EXTRUDER_AUTO_FAN_TEMPERATURE 50
84 #define EXTRUDER_AUTO_FAN_SPEED 255 // == full speed


I found this in configuration_adv.h

I'm not quite sure what was going on but I sliced another model and started printing and my fan no longer slowed down. Maybe Slic3r had something to do with it. Thank you anyways.

In slic3r filament configuration, there is a cooling option. If a layer meets the conditions specified there, it will turn on, off, or change the speed of the fan. The shorter the time it takes to print a layer, the faster the fan spins.

I'm not sure which fan you are talking about . . . the hot end fan, which can cause jams if not running should not be connected to anything but constant 12v power in most cases. A layer fan is controlled by the slicer, but cannot cause jams . . .

? ? ? ?

- Tim

It sounds like you're either using one fan to cool the hotend and the print, or wiring the hotend fan to the print fan output. I'd recommend using two separate fans and wiring the hotend fan directly to 12v output on your power supply.