Well, the autopilot just controls pitch and roll. If you hold the rudder trim long enough in one direction and can't feel in the seat of your pants that the aircraft is becoming completely uncoordinated, the autopilot will apply airleron to hold wings level but it eventually will run out of force to apply and kick off. When that happens, the applied aileron force will go from a whole lot to zero in an instant and the aircraft will violently roll.