Thermostat controls cooling cycles based on the temp sensing by the thermistor (temp probe in the clip attached to far right fin)
Freezer temp should be at least 10*F (colder is better) and food compartment temp below 40*F
A bulb thermometer in glass of water on shelf in food compartment can accurately measure inside temps
The 'tip' of thermistor should just protrude out top of clip
Clip should be tight against fin.
To test if thermistor is issue....unplug the thermistor leads from the lower circuit board.
P2 2 pin connector on top left area.
With thermistor unplugged fridge has no temp sensing so it runs continuously
Let it operate for a least 12 hrs this way.
If issue is thermistor then food compartment will get very cold.....35*f or lower (freezer will be 0*F or colder)
IF fridge does NOT get colder then issue is with ventilation, airflow/draft or cooling unit