Hi, my name is Mike and I have been in the home improvement and repair field for 20 years. I will be very glad to help you today. Either too much ice has formed on the evaporator and the heater is not able to melt it or the heater on the evaporator has failed. This problem can be caused by items in the freezer blocking the vent or the fridge door being left ajar by accident or the heater is failing. The best thing to do at this point is to completely melt the ice from the evaporator with the hair dryer and also wipe the bottom of the fridge and be sure that the condensation drain at the bottom of the fridge is clear. This should solve the issue and if it does not then the heater for the evaporator has failed and needs to be replaced.