How does a speed control switch work? If ya reduce the motor voltage, won't ya burn out the motor? What inside of the controller reduces current without reducing voltage?
I think that the variable speed switches are in fact varying the voltage. But because the motors are shaded-pole, they can handle it. They may run warmer due to the lower voltage, but I don't think it's all that much hotter with the sub-horsepower motors. I've been running mine that way for months, and I cannot feel the increased heat with my hand.
I don't really understand it completely - if we have any experts about this issue maybe they will chime in. Most of the info I've read says that lowering the voltage on a motor is not a good idea, but all that info usually applies to larger motors that use a capacitor start, which shaded-poles don't have. Shaded-poles have a low starting torque, but it's no big deal for blowers, 'cause there's little torque.