Voltage Between Ungrounded Appliance and Ground
Chop the butchered plug off and replace it with a proper grounding plug
Fortunately, the disfavor that the previous homeowner did you by chopping off the grounding pin is fixable.  Simply chop the butchered plug off the cord and replace it with a field-fit type NEMA 5-15 plug, available at any hardware or big-box store.  (Strain relief isn't much of an issue here, as how often do you move the fridge, anyway?)