You should not use frozen beans in a grinder. When you freeze beans, thereis air in the package. This air will become condensation once the beans are thawed causing them to be wet. If you put wet beans into a grinder, you risk the chance of causing internal rust and ruing the unit as well as the taste of your coffee. Wet beans will also cause the ground coffee to clump together causing clogs in your machine which results in the beans not feeding into the unit properly. Your unit will likely require frequent maintenance from this.