Owen,
When you replaced the main motherboard (part#
WR55X10942), did it seem to fix the problem temporarily, or did it start acting up again right away?
The motherboard is what controls the speed of the evaporator fan motor (freezer fan motor). It is normal for the speed of the fan to vary, that is why they let the motherboard control the speed of the fan motor. What is not normal, is if the speed of the fan constantly varies while it is running. Most people seem to describe the fan as making a whooing noise when this happens. It is possible that the evaporator fan motor (part#
WR60X10074) is bad, and it is burning out the control board. Some people when having this type of problem will replace both parts at the same time to prevent any further issues.