Restoring multiple speeds to your auto heater/air conditioner blower by replacing a resistor module is a simple repair.

“HW-687 is one easy module for adding speed regulation to your next DC motor-based project. It is a simple pulse-width–modulated speed controller providing smooth control with almost no jerks. There ...

The smart motor control module—MMP757188-36 in this example—validates the results. Figure 2 The MMP757188-36 is a motor control module for smart motor applications. Source: Monolithic Power Systems ...