No, they are two separate but connected parts of your vehicle's HVAC system.
Diagnosing a faulty blower motor versus a bad resistor typically comes down to what fan speeds are working. If the fan only works on the highest setting, the resistor is usually the culprit. If the fan doesn't work on any speed, or if it makes strange noises, the motor itself is likely failing.
Which one to replace? If high setting works and medium and low do not, replace the resistor. If blower motor is spinning but makes noise, replace the blower motor. If you hear noise and only high setting works, replace both.
No air comes out of the vents
There are instances where a bad resistor will prevent the current from reaching the blower motor altogether. Without any power, the motor won't run. As a result, the blower fan stays still and silent, and no air blows out of the vents.
The average cost for a Blower Motor Resistor Replacement is between $138 and $194.
Blower motor resistors typically last between 5 to 10 years. However, there is no set mileage or exact expiration date. Their actual lifespan heavily depends on usage, the quality of the part, and whether your cabin air filter is regularly changed.
In most cases, yes — replacing your furnace blower motor is a smart, cost-effective repair that can add years of life to your home heating system. If the rest of your furnace is in good condition, a new blower motor can restore proper airflow, reduce energy strain, and help your home heat more evenly.
The blower motor resistor can be removed after the bolts have been removed. The wire should be linked to the blower motor's positive terminal, and the negative terminal should be attached to the blower motor's negative terminal. This will turn off the resistor and allow the blower motor to run at full speed.
The blower motor reset button is usually a small, red or yellow button located directly on the motor housing, inside the blower compartment of your air handler or furnace.
The blower motor resistor is typically mounted directly to the HVAC air duct, usually under the passenger-side dashboard, directly next to or underneath the blower motor housing itself.
The heat exchanger is often considered the most costly part of a furnace to repair or replace. It is a critical component that transfers heat from the combustion process to the air that circulates throughout your home. Over time, heat exchangers can crack due to the constant heating and cooling cycles they undergo.
Signs you need a new blower motor include weak or completely stopped airflow from your vents, unusual noises (screeching, rattling, or grinding), and a burning smell from the dashboard or vents. You may also notice erratic fan speeds, the blower motor continually blowing fuses, or excessive vibrations.
To test a blower motor resistor, set your multimeter to measure resistance (Ohms). Disconnect the resistor and measure the resistance between the common input pin and each speed pin. If you read "OL" (Open Line) or zero resistance, the resistor or its thermal fuse is blown and needs to be replaced.
When a resistor goes bad, its internal resistance changes. It will generally either fail open (stop the flow of electricity entirely) or drift in value (block too much or too little current). This can cause the circuit to malfunction, overheat, or fail completely.
A bad blower motor—whether in your car or home HVAC system—struggles to push air effectively. Common symptoms include weak or no airflow from the vents, abnormal noises like grinding or squealing, strange burning smells, and a fan that works intermittently or stops entirely.
Diagnosing a faulty blower motor versus a bad resistor typically comes down to what fan speeds are working. If the fan only works on the highest setting, the resistor is usually the culprit. If the fan doesn't work on any speed, or if it makes strange noises, the motor itself is likely failing.
Otherwise, clear away any dust or debris with a rag, making sure to work gently. Reset the Motor. Most blower motors are controlled by a red or black switch on the side of the unit. Hold the button down for a few seconds (the manual will tell you precisely how long), then release.
If it doesn't start at all, you can press the button one more time. But, if you press the reset button and your furnace goes on and turns off again, don't press the button again. Continuing to press the reset button can damage your system. Doing so will pump more oil into the furnace and worsen any existing issues.
In this case, we see the resistor value by a multimeter and try to compare it to its actual value. If the measured multimeter value matches the given actual value of the resistor we say the resistor is good, else you have a bad resistor.
A blower motor resistor (also called a blower resistor pack) is a set of high-power resistors—and usually a thermal fuse—mounted in the air stream of your HVAC duct.
What You'll Need
While a fan stuck on high is the most common indicator, a complete loss of fan function on all settings can also point to a failed resistor. In some cases, the entire component can fail catastrophically, often due to a significant electrical surge or extreme heat.
Resistors most often fail open, not closed as in a short circuit. So if you just wanna take a quick and dirty look, you can place a resistance meter across the component and you should get the resistor's rated value OR LESS.
A physically damaged resistor will often show clear signs of overheating or structural failure. Tell-tale signs include charring (black or dark brown burn marks), blistering on its paint or body, visible cracks, or a completely split and broken casing. You might also notice a strong, acrid burning plastic or electrical odor.