If you've had the fridge for a year or more, and you have't checked the condenser coil for a dust layer on it, you should do so. A dust layer blocks the air flow through the radiator, and reduces the efficiency of the refrigeration system.
The coil is located at the bottom of the fridge behind the rear cover panel. If you find a dust/lint layer, vacuum it off with a shopvac, and give the fridge an hour or so to return to normal operation.
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