I have a Subzero 700tf which keeps freezing up on the bottom back. I've taken everything I can out of the inside and can't find any cracks in the liner. Drain hole works fine and it's not the drain pan over flowing. I just cut a small section of the metal open on the lower back and it looks like the sprayfoam type insulation is intact. I had a repair person out twice and he says nothing is wrong with it...as an aside, he was quite arrogant and didn't really look at the problem. My next option is to throw it out and get a new one, but other than this problem, it works fine. Any suggestions would be greatly appreciated.