Heavy frost buildup on the evaporator coils is a common reason why a fridge stops cooling properly. In this case, the defrost system isn’t doing its job, which forces the unit to work twice as hard without actually dropping the temperature. We used a steamer to carefully clear out the ice and then tested the defrost heater and thermostat to find the root cause. Getting the airflow back to normal is much more cost-effective than letting the compressor burn out from the extra strain.