Cools but doesn’t stay cold

When you say you come back later to check on it, is it not running when you check on it?

It almost sounds like the thermal overload in the control is tripped when you turn it off and back on. That’s how you reset the overload. A very common issue for any fridge is to have the start relay fail to send a pulse of electricity to the start winding of the compressor motor. That causes the motor to sit there and hum, stalled. That draws a lot of current and the overload trips to prevent damage to the motor. Have you ever heard it hum loudly for a few moments when it goes to start up, then you hear a click? If you’ve heard that, I bet the start relay has an issue.

It’s really hard to say with any certainty what is going on if you haven’t been around it to see what happened. You would really need to pay close attention to it to see what is going on. Plugging in a kill a watt meter to the fridge will allow you to see the current draw of the motor to be able to determine if the start relay is working correctly or not. If the start relay is failing to send a pulse of electricity to the start winding, it will draw a lot of current and be stalled. You would probably see 10-15 amps or more on the meter and then the overload should click to avoid damage to the motor. If the amperage hovers around 2-3 amps always and it just turns off and never turns back on, without a failed start attempt, it could be a thermostat that is sticking.

There are new relays available that can replace the one in it, a Supco RO81 is a popular choice, but replacing the relay will also mean that the machine needs to be re-wired. There is a thread and linked video on here which shows how to completely go through one of these and re-wire it. The wiring is probably crumbling apart and could very well be a fire hazard. As someone who has almost had a fire start from bad fridge wiring, trust me, you don’t want to leave it in place forever.