I have purchased a home with a Subzero 700BR (two refrigerator drawers) that are not cooling below 55F. They are from 1997 (no warranty remaining according to Subzero) The Subzero tech advised the worst, and likely, case was a sealed system replace at $900. I just can't afford that with a new home and newborn twins, so I downloaded the repair manual and have been reading all I can on this site. While I have successfully repaired dishwashers and dryers, refrigeration is clearly the highest level of enlightenment.
The compressor seems to run as does the condensor fan. The thing is quite quiet - i'll give them that. Evap fan is not running with drawers out. However, after 20 minutes there is only a touch of frosting, and the evap is coolish - not cold.
From the flow chart I think this pattern means either weak compressor or low refrigerant. If anyone has advice for a next step, that would be most appreciated. Replacing the unit is $3,999. Even more out of the question for us. It is marked 134a refrigerant on a tag on schrader valve if that matters. Thank you all.