A fridge runs from on of three things,
1. It's not cold enough, (check temp), see if inside is really cold, then try moving thermostat to max warm and see if it turns off.
2. Thermostat broke; previous check may give a clue, if fridge is really cold, and still running there is either a probe, or a bimetal strip thats supposed to open when it reaches temp if it is blocked by food
or ice, or a seal leak it may show fridge warmer than it is.
3. Bad compressor
or incoming voltage is too low. if the previous two checks are both negative, you may have to call in a tech to check freon levels and compressor
. But before you do insure it is getting the proper voltage under load, (at least 12volts).