Bottom frezzer is working but fridge is not blowing cold air
Refrigerator gets cold air from freezer compartment. Either the air flow is blocked by food items or ice, or the recirculating fan is not working.
The most common failure is that the freezer coils get all iced up becuase the defroster timer, defroster thermostat, or heater has stopped working.
When it's running, you should feel cold air blowing out of the vents that are in the fridge, otherwise, the 'air tower' (air vent) is blocked with ice.
If you manually defrost the whole thing, and it runs fine for a day or so, then it's not defrosting properly. If you manually turn the defroster timer, and you don't hear the scorching/hissing/gurgling of the defroster working, then that would confirm a fault in the defroster circuits.
Based on the following thread, it's probably a bad defrost thermostat.