Leaking evaporator job's make up for most of our Sub Zero no cool complaints. Over time the evaporator will break down and the freon that is inside will slowly leak out. When this happens you may start to notice you have to turn the control colder and colder. Another sign is if you notice frost in the upper left hand corner in the refrigerator. When freon leaks out it will create a frost ball on the capillary tube, in turn creating visible frost on the back panel of the refrigerator. This repair should only be done by a professional certified CFC technician. To handle freon you must be certified. Sub Zero condenser fan motors will often fail, when doing so it will create a no cool condition. To verify the operation of the condenser fan motor remove the grill assembly. There are several screws coming in from the bottom side of the of the grill once removed the grills top will pull forward and reveal two springs, remove the springs and grill will lift off. Certain Sub Zero refrigerator's and freezer's grill's are removed by lifting straight up on the panel, the bolt heads slide out of the metal bracket. With the grill placed safely out of the way, you will see the fan motor in the middle up top. The fan is situated in the middle, this enables the fan to cool both the compressor and the condenser. The fan should be running when ever the compressor is turned on, if the compressor is running so should the fan. If the comp is running and the fan is not you more than likely have a failed fan motor.