A surgical apparatus comprises a body, a user input feature, a shaft assembly, an end effector, and a blade cooling system. The end effector comprises a clamp arm and an ultrasonic blade that may be coupled with an ultrasonic transducer. The clamp arm is configured to pivot toward and away from the ultrasonic blade. The cooling system is operable to deliver liquid coolant to the ultrasonic blade to thereby cool the ultrasonic blade. The user input feature is operable to both actuate the clamp arm and actuate the cooling system.