Blower Motor Resistor Replacement
What is a blower motor resistor?
The blower motor is a fan housed in the heating, ventilation and air conditioning (HVAC) ducts, normally located behind the glove box. It uses a resistor to change the speed at which the fan operates.
How does the heater blower motor resistor work?
The air conditioning and heating controls allow you to switch fan speeds — and the blower motor resistor controls that speed once you select it. The resistor is between the power source and the fan, and allows only the desired amount of power to go to the fan. When the fan receives less power, it turns slowly, and when it receives more power, it will speed up.
Often when the heater blower motor resistor fails, the blower fan will operate only on the highest speed and none of the lowest speeds.
What are the symptoms related to a bad heater blower motor resistor?
When the blower motor resistor fails, the air conditioner and heater may still work, but air may blow from the vents at only some of the fan speed settings.
If the resistor isn't replaced for some time after starting to act up, it may fail completely, leaving the entire system useless.
Can I drive with a heater blower motor resistor problem?
Driving with a defective blower motor resistor can be inconvenient, but there's no safety risk. If it has failed completely, you won't be able to use the heat, A/C or even the fan, so that won't be fun during extreme heat or cold.