Does anyone have an idea of why during defrost cycle on a ARNEG Dairy Chiller temperature is staying between 11 & 12 degrees and sometimes rising to 20? The cabinet defrosts 3 or 4 times a day and then pulls back down. It has a remote condensing unit running on 404A suction pressure 34 PSI gives me an evaporating temperature of about -17 to maintain refrigerated temperature.

When it was installed, I believe the customer was told the thermostat should read no more than 5 degrees. Is there a part such as a bimetallic klixon that can be replaced to cure this? Electric defrost is not my strongest point but I know the defrost cycle is lasting about 45 minutes to an 1 hour.