When I had a problem with the heating and air conditioning in my car, I had to figure out how to solve the problem myself. I had recently lost my job, and I was struggling to pay my student loans, home mortgage and health insurance. I couldn’t afford to pay a mechanic to fix the HVAC in the car. I figured out that the problem was mostly likely caused by the blower motor resistor. Since I had no clue what the blower motor resistor was, I needed to do some extensive research. I learned that the blower motor resistor regulates the speed of the fan for the heater and air conditioner. The blower motor runs the fan, and the resistor is used to reduce the blower motor speed. The blower motor resistor is usually installed near the blower motor, and very often inside of one of the air ducts. I was already confused, and then I found out the blower motor resistor is actually made up of three or four small resistors constructed on a circuit board. The component doesn’t require any maintenance, but if it malfunctions, it will need to be replaced. Unfortunately, my resistor was no longer covered under warranty, but it did need to be replaced. The resistor is installed inside one of the ducts of the HVAC system so that the air flowering through can cool down the resistor. Changes in temperature and humidity can lead to corrosion of the resistor. There is also the possibility that a foreign object can obstruct the fan blade, causing increased current and overheating. Most often, if the resistor has malfunctioned, the fan will only work at the highest speed. This is because the current completely bypasses the resistor.