An air-actuated fan clutch having a translatable piston in communication with a pressure chamber and moveable between a piston neutral position and a piston activated position in response to air pressure. A clutch spring biases a clutch housing into engagement with a clutch element that is coupled for rotation with a drive shaft when the piston is in the piston neutral position. Movement of the piston to the piston activated position moves the clutch housing away from the clutch element to inhibit transmission of rotary power through the fan clutch. A valve and an actuator are provided to prevent movement of the piston from the piston neutral position when air pressure acting on the piston would be below a predetermined threshold.