I put a cover over my air-conditioning heat pump to keep leaves and rocks out of it. However, somehow something got in there. There was a loud banging. I turned off the air conditioning to the house and looked under the cover. There was a severed tail at the bottom of the unit and some sort of lizard or frog chopped up and stuck in the grading on top. Apparently it kept bouncing off of the spinning blades, sticking to the grading, and eventually falling back into the blades. I cleaned out the creature, and restarted the unit. Fixed.