Do not know the model, but just done a search, unfortunately some bad reviews.
Check around the compressor motor in the back, if it has a fan there, make sure it is clean and operating, might be a tray on top of motor, with a pipe going to it, make sure pipe in trough, that is your defrost outlet. Some comments about noise at back of frezer unit, so that would be where the fan is, You may need to fully defrost it to check, I believe auto defrost, but if auto not working, will give you the problems you have. So unpack all, into thick boxes etc etc wrap every thing up to avoid loosing food, Defrost fully, DO NOT chip ice out, after switching it off. hair dryer, on low, but keep the dryer out of the unit, Do NOT want water dripping into it, low heat is better, When fully defrosted try it, dry as much as possible before switching it on, any water droplets will just freeze, and create problems. If that works, Auto defrost system faulty, Could be just a sensor, or.
SD, January 2012