Thanks for the replies, guys.
Niobrara, there are no signs visually of Freon leaks but the areas visually inspectable are limited. The compressor is running via sound and vibration. I agree that a bad thermistor should only affect one side and both sides are affected. Since the display indicates the freezer temperature at 22 degrees (the freezer in reality is probably at 50 degrees or more though) and the FF side shows at 58 degrees on the display (likely accurate) you'd think it would be running the fans on both sides with both sides well above setpoint and also the compressor should be at at full bore at those temps too. It really doesn't seem possible to measure the compressor voltage since it is inverter driven which means it is likely a square wave rather than sinusoidual and also the compressor says it is a 240 volt unit even though the fridge is operated off 120 volts. There's no way to know what the voltage to the compressor should be given these things, at least without factory documentation. The ability to see the input and output conditions from a diagnostics mode would be of great value but alas I can't seem to find a manual for this unit. Also the ability to force a known cooling mode would help too. Once again you'd need a manual.
JW, thanks for the video, I've added it to my library. Very good video!
And RegUS, thanks for your input as well!