1. The fridge isn’t cooling well.
Assuming the door seals are tight and the condenser coils are clean, there could be a problem with the thermostat. (Check the freezer for frost; that’s a telltale sign.) This is the best-case scenario, as a new thermostat will run only about $200. Worse? It could be the compressor. That’s so expensive to replace ($500 to $700), it might make more sense to buy a new machine.
2. There’s a puddle under the refrigerator or moisture on the seal.
The mullion heater—a mini heater embedded in the unit, which counters condensation—may have burned out. Or you may have a faulty door seal.
3. The fridge is making strange noises.
If you hear thumping, the compressor could be shot (see above). If it’s more of a squealing sound, you might need a new freezer fan, which will cost about $200.