My Whirlpool fridge freezer WRF560SFYB00 is making a very loud noise. It comes from the fan in the back of the freezer. If I blow heat from a blow dryer into the vent covers of the fan, water begins to drip from it and the noise will stop for a while. It has been progressively getting worse, and now using heat on it only keeps it quiet for a little while. There has been an increasing amount of ice building up in the back as well, and I have the freezer on the lowest setting. Also, it seems that the more the freezer door gets opened, the sooner the sound starts and the louder it gets.

Thanks in advance for any ideas on what is wrong here.