Just moved into a house that has a 1992 Subzero 550 built-in (serial number M989921).
1. Loaded up the fridge and freezer with food and noticed several days later that ice cream is soft and fridge is warm (60 degrees F).
2. I turned both temperature settings to 10, but that did not seem to make a difference.
3. Removed grill and vacuumed condenser which had some dust but didn't look too bad. Freezer temp is about 7 degrees, but FF compartment still warm.
4. Confirmed condenser fan is always running.
5. Confirmed both compressors are hot to the touch.
6. Removed Fresh Food evaporator fan cover and confirmed that when the right-hand switch is depressed, fan turns on.
7. Removed back wall of fresh food compartment and the top half of the evaporator has some frost on it with build up and the extreme right and left-hand sides.
Because there is a separate compressor for the fresh food and freezer compartment, my understanding is that there is no defrost cycle for the fresh food compartment. Is this frost build up a consequence of low refrigerant (R12) which indicates a leak and possible evaporator replacement, or could this be due to something more simple?