You have 3 wires from the motor, one is black and gets attached to the housing which is attached to the body grounding system. Do you have a ground strap from the engine to the firewall?
The other two wires are the separate high and low speeds. You should never have power on more than one lead. If you energized both power leads to the motor I think the circuit breaker will open. I would say you have a wiring problem in the console. If I remember correctly the motors operate in unison or you wouldn't be able to clear the windshield on both sides as each side has a mechanical diverter for defrost and cabin heat that operates with one lever for both.
Barry Wolk
Farmington Hills, MI
C5681126