I've seen a number of defrost posts and already know a few things to try but here is my story.
Two years old, in use refrigerator. At 1.5 years starting hearing a fan tick-tick-tick noise and noticed ice in the 'vents' within the refrigerator section. youtube search lead to unplugging the fridge, letting it warm, with a little hair dryer help, until the ice melted. Happened again two months ago; happened two weeks ago. I can now feel a bit of ice in the 'vents' (normally styrofoam) and I suspect it will happen again.
What are the suspects in this problem? Would the diagnostic codes tell anything at this point? Would a manual defrost get us past the upcoming freeze over? Is there a sensor to relocate?