How is the resistor block used to provide multiple fan speeds?

The resistor block is utilized to provide multiple fan speeds by reducing the voltage supplied to the fan motor. When different resistors in the resistor block are placed in series with the fan motor, they lower the voltage reaching the motor. This reduced voltage alters the speed of the motor according to the characteristics of electric motors, whereby a decrease in voltage results in a lower operating speed.

As the resistor values are changed, or as different resistors are selected through a switch, the amount of voltage going to the motor can be varied, allowing the fan to operate at different speeds. This method is common in many automotive applications where a straightforward and cost-effective solution for fan speed control is required. The simplicity of this system is advantageous because it often requires no complex electronics, making it easy to repair and maintain.