I started renting my current apartment 3 months ago. The fridge is newer and nice but ever since I moved in it makes thwocking noises like someone is inside of it throwing rocks at the door. They are very loud!
I haven't been too worried until I opened up the freezer(top) section yesterday and heard a dripping sound followed by a hissing, then a crackling noise. Like water falling onto a hot surface. The fan-freezer was on at the time. Hasn't done it since then but I'm worried it is the beginning of something major that will cause the fridge to fail or something even worse.
Thanks for any suggestions or possibilities. I will pass them along to my landlord.

Gee it sounds like it was in defrost mode while running. If your renting, notify your landlord or the property manager of this. You should not be liable for repairs.