What is wrong with my fridge?

*There is a distinctive clicking noise coming from inside the fridge where the light bulb screws in. I’m not sure what’s in this plastic enclosure but the thermostat is nearby – possibly a broken t-stat?

*Cold temperature in refrigerator is not being maintained. It is much warmer than it should be.

*Ice crystals are forming in the freezer. This suggests to me a possible condensation problem inside the freezer, but also it seems like when you crank up the thermostat in the fridge, the fridge temp stays the same (at a temp too warm) while the freezer gets colder or where most of the cooling is going to the freezer.

*Sounds like it is running normally until you open the fridge and hear the clicking.

*This is a typical fridge – small freezer on top, larger refer on bottom, single door.