Thanks for the quick help.
I have configured the cooling zone as a thermostatic fan for now. It seems to stabilize right above the T parameters and that's at least good enough right now. I'll do some tweaking with the pwm range to have it settle betwenn the T values of M106.
The biggest issue before was unstable temperature, so at least that's fixed.

The PWM inversion with M307 didn't work for me. I've also tried to invert the pins unsuccessfully. I think for that feature I'll wait for the FW update.

@droftarts
I thought the temperature range of a thermostatically controlled fan was not really what I wanted because I want to set a precise target temperature. But this may actually work if the temperature range is setup very narrow and pwm window is tuned so no swinging occurs around the target temp.

@LB
The problem with inverting the pin may be temperature errors. But maybe I'm wrong here. Advantage would be more logical slicer start codes and easy control in DWC.
I'll try that version first.

Hi everyone,
Is it possible to configure a heater so that it cools instead?

In a screw-based extruder I want to add an actively controlled "cooling zone", similar to other heater zones.
I have a 24V PWM controllable water pump and plan to use a fan or extruder output to change pump speed. A higher PWM duty cycle rate should lower the temperature of the assigned temperature sensor.
Also temperature errors should be ignored for that cooling element in case the cooling power doesn't suffice.

In theory this should be straight forward to configure. However, I am not able to find any info about a setup like that and standard G-Codes don't seem to work.

Can someone think of a solution or a clever workaround for this setup?
If necessary I'll also dig into the firmware to make changes here.

Thanks for the help!