I have a Sub Zero Model 550 with the freezer
in the bottom. The fridge works great all the time. The freezer forms frost and ice on the top, which causes it to not maintain it's temperature even if you keep lowering the control. I have defrosted it manually many times, but each time it takes about 4 to 6 weeks and the situation repeats itself.
JA: Can you guesstimate how old your Sub-Zero is? And just to clarify, what's the exact model?
Customer: It is a Model 550 that was built in 1993.
JA: What are all the symptoms of the problem (error codes, flashing lights, etc.)?
Customer: I don't know of any error codes or flashing lights. The earliest symptom is that ice cream no longer stays frozen really hard, instead becoming somewhat soft. After a week or so like this, the ice maker
will stop working because the freezer isn't cold enough.
JA: What happened just before this problem started? What troubleshooting have you tried?
Customer: Nothing. It has been doing this for a long time. I have cleaned the condenser on top. I fully defrost it about 6 or 8 times a year in order to make it work. I have inspected the gasket, which seems fine, and have put lubrication on it to keep it soft as instructed by a technician a few years ago.
JA: Anything else you want the appliance expert to know before I connect you?