Samsung French door refrigerator. Refrigerator compartment was working but freezer running a little warm and neither ice maker making ice. Digital readouts for temperatures for both fridge and freezer holding to set point. Pulled the cover to the freezer evaporator coil and found it frozen up, blocking air flow across coil and to air circulating to ice makers and freezer compartment. Testing found defrost heater and thermostat both bad (heater open circuit, thermostat on all of the time). Maybe thermostat went first and wore out heater by being on all the time? Don't know. Replaced both. New heater element tested at 55 ohms, in range from a video DIY. I really found the drawings for the Samsung and other DIY info on AppliancePartsPros.com to be helpful in identifying and replacing. It's only been 4-5 days since I replaced the parts, so I feel like the jury is still out, but it's been a good 4-5 days so far, making ice, and freezer compartment staying cold.