Not necessarily. The speed control is just a variable resistor that drops some of the voltage before before it gets to the heater blower. There's no electrical connection to the bracket, so grounding isn't an issue. Be aware that sucker will get HOT however! If you touch it anywhere except the knob, you can get a nasty burn! A bare leg against the switch housing will sizzle like bacon in a skillet. Your lady friend who's taking a ride with you will not appreciate getting a burn scar there!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!