Hello. I have come across this issue on many, many websites. The evaporator fan speeds up and slows down, and when it slows down, makes an annoying whistling noise. I haven't actually measured how much the temperature in the freezer fluctuates, but there are times when things are 'soft', and it's causing the ice cubes to stick together.
So, I replaced the evaporator fan motor. Didn't fix the issue. So about a week later, I replaced the main circuit board. The issue still persists.
I'm wondering if there are any other common fixes for this problem, aside from buying a new fridge. I've already sunk $300 into it.
I should note that while I replaced the fan motor, I did not replace the thermistor. Don't ask me why I didn't. At the time I wasn't clear on its function, and to be honest, I'm still not. Could this be a cause?