Hi... I have a Kenmore top freezer model 253.71822106. I few weeks back I noticed some condensation (and re-freezing) building up on the top shelf of my fridge. I just dealt with it, but now it has stopped cooling altogether (I'm not sure if these are related, just giving back info). The compressor runs (and gets warm), as does the freezer fan, but the evaporator coils do not get cool. I've checked the following items: 1. temp setting 2. airflow 3. vent airflow restriction 4. temperaure control continuity 5. condenser coil cleanliness 4. door seals 5. door switch continuity 6. defrost heater resistance (25ohms) 7. evaporator fan 8. drain tube 9. defrost timer (although I'm not sure about this one, it seems to work, but it has a capacitor in series, so I checked it in parallel and it seems to be OK?). I'm to understand that the refrigerant system is sealed, so a leak is very unlikely... so I'm not sure where to check from here. Any help would be appreciated.

Your cooling system is out of refrigerant. You need to find the leak, rectify and refill the refrigerant.

The problem is very common with some freezers.
It has run out of GAS.
It must have a bit of a leak in the gas system.
Get a professional to re-gas it.
Saves you from a big investment in getting a new freezer.