I work on many Sub Zeros and have always been able to diagnose and repair any problem I have run into. This model is a old RFD361, in great shape for the age. I have worked on this refrigerator a few years back for this customer. This model uses a single compressor to refrigerate both sides. Customer complaint was freezer @7 fridge @ 45 degrees. All fan motors were running, no defrost problem, clean condenser, lights going off when door closed. I put my gauges on it and have a back pressure of 10 psi, a head of 150psi. Cut out is 2 psi cut in 15 psi. So I figure the compressor is a weak.
I installed a new compressor and changed refrigerant to 134A. Customer calls back says temp are about the same. I go back and have a back pressure of 5 head 150 ish. To confirm enough refrigerant, I looked at both evap coils and they are fully frosted by a thin film of frost, normal frost. And oh yea, the ice maker was not stuck in harvest

So the compressor is fine, stat , defrost working OK, all fan motors good, and confirmed no electric heaters of any kind on while in refrigeration. Can you guess what it was? I never ran into this problem but I got it fixed.

A hint: when I unplugged freezer fan, the fridge temp went down. No air leak problem either, door gaskets and cabinet seal good.

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http://www.dependable-refrigeration.com

Sounds suspicious to me.

Did you confirm the temps with your own thermometer? Or is it possible the customer is using an uncalibrated thermometer?

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Econo Appliance Service - San Diego appliance repair experts!

You state that refrigerator temperature started dropping when you stopped the evaporator fan which would lead to an air flow problem.