An ultrasonic surgical instrument and method of limiting an ultrasonic blade temperature includes adjusting at least one power parameter of the ultrasonic energy in response to reaching a predetermined frequency parameter change threshold in the ultrasonic blade limiting the temperature of the ultrasonic blade to an upper temperature limit. The ultrasonic surgical instrument further includes an end effector having an ultrasonic blade, a jaw, and a controller. The jaw is movably positioned relative to the ultrasonic blade and configured to move between an open position and a closed position. The controller operatively connects to the ultrasonic blade and is configured to measure an ultrasonic frequency of the ultrasonic blade. The controller has a memory including a plurality of predetermined data correlations that correlate changes in measured ultrasonic frequency of the ultrasonic blade to a blade temperature of the ultrasonic blade.
