Well, I don't know for sure, but I suspect these window motors are shunt wound type. They are designed to turn at a constant speed regardless of the load. So, even as it gets harder for the motor to move the regulator, it doesn't slow down, it just draws more current. When I had mine on the bench and out of the car, it drew between 2 and 3 amps from a regulated power supply. run / start. But that doesn't mean yours should be the same.

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