Side by side GE Freezer problem

I have a GSS201EPhWW side by side fridge that is giving me issues. A few weeks ago I turned the freezer all the way up to nine and when I turned it down the fan quit. Managed to get that going again, but the freezer has a wide variation in temp, anywhere from +7F to -10F and is running a long time. The other night it would not shut off on its own, so I wound up shutting it off overnight and it started up and ran good but still with a wide variance of temp. I have it set at 1 The fridge is set at 1 also and is not freezing up. Was wondering if it was the thermostat or what? Any ideas?

Is the condenser fan in the back of the unit by the compressor running when the compressor is running? Any frost on the back wall inside the freezer?

No frost, condenser fan and evaporator fan is running. Did have a problem with condenser fan, but got that started after a few days.Everything else seems to be fine.

What temps are you reading in the fresh food section? It sounds like it’s either a bum thermistor or maybe a bad damper. Do you have an ohm meter? You can ohm out the thermistors to check them if you do. Look for an open or shorted one. Can also take the unit apart and have a look at the damper to make sure the flap didn’t break or come loose. I’d start there and see what I found.

The fridge is reading around 40F set a 1. Been making me crazy. Really appreciate all your help. Was thinking the thermistor or the capacitor. Will check that out.