Description

Heater Resistor Pack – the blower-speed control resistor in the heating and ventilation (HVAC) system.

It sits in the heater blower circuit between the fan speed switch and the blower motor, dropping the supply voltage to set the lower and intermediate fan speeds; each switch position selects a different resistance, while the highest setting feeds the motor directly. A failed resistor pack is a common cause of losing one or more of the intermediate blower speeds while the top speed still works.