Why does my Heat/AC only run on one setting?


The blower motor powers the fan that allows hot or cold air to flow from the vents in your vehicle. It is the life of your HVAC system. Without airflow, you won’t have properly working heat or air conditioning. The blower motor is inside your dashboard, usually opposite the steering wheel. So, what does the blower motor have to do with a fixed high airflow?

The blower motor works in conjunction with a resistor. The resistor uses voltage to control the output speed of the blower motor. The blower motor resistor is prone to shorts, corrosion, and overheating. When the resistor fails, typically, the highest setting is the only option that still functions. This is because the air from the blower motor is bypassing the resistor, thus gaining the maximum amount of voltage, resulting in full power. In other cases, there could be an issue with your AC module or the fan switch. With the resistor sometimes located in a hard-to-reach location, it’s best to go to a trusted auto shop for a proper diagnostic. Bring your vehicle to Ferber’s Tire and Auto for a diagnostic today!