Another issue to check if your fridge is not cooling as well as it had been, is the little thermostat fan switch that is attached to the cooling fins outside at the top of the fridge. It senses when the cooling fins get hot and turns on the factory fans to keep the air flow going in the right direction, up. I discovered a while back when the fridge was not working as well as it had been that the fans were not working, so I jumpered the switch out and the fans came on. I replaced the switch and the fridge is working great again.
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