what is wrong with fridge compartment of my daewoo american fridge freezer?

Without a specific model number it's difficult to give a precise answer, but a problem like this would normally be caused by failure of the circulation fan in the freezer compartment. This will probably be hidden behind panelling at the upper rear of your freezer and upon removing you will find a vent that leads to the fridge side. Replacing the fan and motor should fix your problem.

Rupert
June 2017