15 month old fridge/freezer not cooling
Based on the information you provided:
- Compressor is running
- Freezer is not cooling
- No freon loss 
- Condenser fan is working OK
- Low compressor temperature
- Condenser coils at room temperature

First of all, check the condenser coils and if they're dirty clean them as much as you can, THE CONDENSER COILS SHOULD BE WARM!!! . If that doesn't work, check the condenser and the evaporator fan motors.

If not, Could be an array of things related to the compressor and coolant:
- faulty solenoid valve of the compressor.
- blocked filter at the expansion valve
- Evaporator inlet solenoid closed
- Compressor capacity control faulty leading to less coolant effect across the thermostatic expansion valve.

The way fridges/freezers are built today if there's a problem with the compressor, a valve or something is wrong in the circuit, you should go for a new one.