Good compi, the resistance works for the first three speeds, the fourth or stronger is direct from the switch or potentiometer. This resistance will be found in the same compartment where the Blower or Advanced heating is housed since it is cooled with the same air flow. It is generally straight, no more than four centimeters and screwed with two screws. Note: The signal from the potentiometer to the resistance is negative non -positive. Insurance resistance has four lines, there are three negative inputs that arrive from the first three points of the potentiometer, but a return that goes to the Blower engine. SALUDOS !!!!!!!!!