Refrigerator running but not cooling.

Probably poor pumping.

Check the evap coils,if iced up real bad,could be that defrost timer isn`t putting it into defrost,therefore the inside fan can`t blow cool air into the refig. Space, does it seem to be running all the time, a temp. quick fix is to locate timer and turn knob and manually put it into defrost ,you will hear it click until the unit cuts off and around 16 to 20 minutes it shound kick itself back on, you may have to do this 2 or 3 times to get the ice melted,, but you will still need to replace the defrost timer

Also could be bad compressor, running but not pumping, check 1st note first