Ice keeps forming inside on the back panel of mysubzero model 550

If the ice is on the back panel especially a block of ice in the middle left part of your panel, then you have a sealed system problem. Check to make sure that your condensor coils above the refer are clean, and if it continues to have an ice block then you have to have a technician come out an do a major repair. This is not something you can do yourself, most subzeros have a 6 to 12 year sealed system warrantee that covers either all of the repair or just parts. This is an expensive repair if it is not warranteed, but when the refers cost 8000 to 10000 new it is usually well worth it. Most often it is the result of a slowly leaking evaporator, though most inexperienced technicians replace the compressor first, so make sure you use an experienced Sub-Zero technician. Good Luck, Appliance Specialits

The reason for the ice forming, is the drain tube is blocked causing water that normally drains-away to freeze.i usu pipe cleaners for this job atach a couple together and run them down the drain pipe to clear it do this every couple of months and you will have no more problems.adrian;;;