I have a Whirlpool ET16AK1M that I inherited from my parents and has been running in my basement for about 3 years without problem. Just the other day we noticed that the items in the freezer were beginning to defrost and removed everything to salvage the food. The unit kept running but was not cooling either the fridge or freezer compartment.

The compressor seems to be running fine (feel vibration and heat) as do the fans internal to the fridge/freezer. I removed the back panel in the freezer and found that there was a good bit of frost on the cooling coil right where the refrigerant line enters but the rest of the coil doesn't seem cold at all. This leads me to believe I'm getting cold fluid up to the freezer but that it's not flowing. There's a small device clipped to the area where the frost develops and it plugs in to an electrical connection. Not sure if this is somehow preventing the refrigerant from flowing? My guess was that it was just the defrost thermostat.

Any thoughts on how to get the rest of the coils cooled?