Why does my heater fan only work on high?
Resistor module replacement Most car manufacturers use a series of resistors to make the heater blower motor run at different speeds. And when one or more of these resistors burn out, you’re usually left with only one heater blower motor speed—high. The resistor module is easy and inexpensive to replace.
What would causes a blower motor resistor to go bad?
In most cases, a blower motor resistor fails due to corrosion or overheating. Sometimes, the mechanical resistance to the motor rotation causes an excessive electric current that can overheat and prematurely damage the blower motor resistor.
Why does my blower only work on high speed?
However, most car makers bypass the blower motor resistor completely when you move the fan speed switch to high. If your blower only operates on its highest speed, chances are you have the series type of blower motor resistor. This is the most common failure mode. To repair the problem, simply replace the resistor block.
How does a 3 speed blower motor work?
Older style blower motor resistor with exposed resistor elements. The blower motor resistor is what’s responsible for giving you three blower speeds. The resistor block contains three different high resistance coils. Think of these coils like a filament in a light bulb.
How to avoid YouTube with blower motor fan?
To avoid this, cancel and sign in to YouTube on your computer. Diagnostic training videos and content hosted by ASE Master and L1 Certified Technicians. Our goal is to teach you ways to be quicker and more efficient in your diagnosis by implementing different techniques and tools.
What happens when the resistor on a blower motor fails?
The coil resistance causes them to heat up, thereby reducing the amount of voltage that can flow to the blower motor. When a resistor coil burns out, you lose that fan speed. A blower motor resistor can fail in several ways; since many are designed in series, if one resistor fails, you loose speeds 1-3.