I've been reading all I can find about this problem, and none of the solutions seem to apply to my refrigerator.
1.The symptoms are the same: the freezer is still cold, but the refrigerator is too warm. Turning up the refrigerator temp did not help.
2. This model does not have defrost heaters. There is no auto defrost option.
3. The coil behind the panel in the back of the freezer is NOT loaded with ice.
4. The vents between the refrigerator and the freezer do not appear to be plugged. No food was blocking them either.
5. The fan in the back of the freezer compartment was not running. I unplugged it and tested the voltage at the plug, and found 117 volts. I assumed that meant the fan was bad, so I plugged it in to confirm it - and the fan ran, for about a second or 2, and then shut off.

Now I don't know where to look. All of the answers I can find online keep pointing to the auto defrost system in refrigerators that are iced up - I have neither.