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Signs of a Bad Blower Motor: Your Ultimate Guide!

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A blower motor is an important component of the car’s HVAC system. It is an electric motor connected to the fans. It runs these fans to move air through the car’s heating and air conditioning system. As important as it is, blower motors can fail over time due to the wearing of the brushes inside it. Its bearings can also become faulty due to insufficient lubrication, causing it to dry which can lead to friction. Signs of a bad blower motor include weak airflow, unusual noises, blower fan only functioning at certain speeds, no airflow from the vents, smoke, and burning smell while you are driving.

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When you notice any of the signs of a bad blower motor, you should have your car checked immediately. The problems can be caused by issues with the fan relay, blower motor resistor, and climate control switches. Plus, bearings inside the motor that have failed because of low lubrication can lead to friction that can eventually cause the motor to seize. To correct the problem and get rid of the signs of a bad blower motor, you will have to replace your car’s HVAC blower motor.


Signs of Bad Blower Motor: What is a Blower Motor on a Car?



Before we discuss the signs of a bad blower motor, we need to understand the role of the blower motor on a car. Most of the vehicles on the road today have a heating, ventilation, and air conditioning or HVAC system. The primary purpose of this system is to help keep the passengers of the car comfortable. One of the important components of the HVAC system is the blower motor. This motor acts as the primary electric motor that is in charge of blowing air through the vents.


The blower motor is the one that runs the fan in the HVAC system. It has a blower resistor or a blower motor control module which is responsible for controlling its speed. The blower motor resistor and switch control it, making it capable of operating at several different speeds that can aid in regulating cabin temperatures.


Basically, the main purpose of the blower motor is to provide airflow over the heater core to create heat during winter and over the evaporator to supply air conditioning during summer weather. The interior vents in the cabin of the car help circulate hot or cold air throughout the cabin, making the ride more comfortable. Although there are some cars that have no air conditioner system, they may still be equipped with a blower motor assembly to allow the circulation of outside air inside the car’s cabin.


The blower motor is usually found in the heater box or inside the dash. You will usually find it inside the engine compartment on the firewall or on the steering wheel’s opposite side. But it’s location can vary depending on the car’s make and model. There are some blower motors that can be accessed easily, while some are hidden under the dash.


SUVs, vans, and other large vehicles are sometimes equipped with more than one blower motor. If you own these kinds of vehicles, you will usually find one blower motor in the heater box’s front and one can be found somewhere in the vehicle’s rear part. You may also spot another heater core installed somewhere in the rear part of the passenger compartment.


So how does a blower motor work? The blower motor’s function is pretty straightforward. The motor will spin when the right voltage is applied which causes the fan to spin as well. The fan can move quite a large amount of air at high velocities since the blower motor is securely bolted in place.


The speed of the blower motor can be controlled by a speed selector, allowing you to turn it up or down, which can be done through its components such as fan relays and blower motor resistors. The blower’s airflow can also be used to either cool or heat the passenger compartment. When the passenger needs heat and turns on the heater, the airflow from the blower motor will be channelled to pass through the heater core which causes the air to heat up. The hot air will then be blown out through the air vents. On the other hand, when the passenger needs cold air, the airflow will be channelled through the AC evaporator.


Signs of a Bad Blower Motor: What Happens When the Blower Motor Goes Bad?



The blower motor plays a very important role in the car’s heating and cooling systems. But, just like the other components of a car, it can become faulty over time. When it does, it will be very hard to take control over the passenger compartment’s temperature. What happens when the blower motor goes bad? Although a bad blower motor does not really have an effect on the overall operation of your car, it can have a significant impact on the comfort level of the passengers, especially when the temperature while you are driving is a bit extreme.


When the blower motor becomes bad and you experience signs of a bad blower motor, it is usually caused by a number of reasons. It can become faulty when there is an issue with the fan relay, blower motor resistor, and climate control switches. When these components have problems that can result in the voltage not reaching the blower motor, then the motor will not function or spin.


The blower motor can also fail over time due to normal wear and tear. There are brushes inside the motor that can suffer wear which can lead to a reduction of power produced by the motor. The motor’s bearings can also become bad because of low lubrication. When the bearings don’t get proper lubrication, it will start to dry which can cause friction and heat and this can cause the blower motor to become faulty.


It can also happen that the blower motor fails to function when the fan cage is blocked. This can happen when an object has fallen down into the dash vents. This can also occur when a small animal finds its way into the heater box along with a lot of dirt or debris. When this happens, you may have to clean the fan cage in order for the blower motor to work again.


When your blower motor goes bad, you will most likely experience the symptoms or signs of a bad blower motor. The signs of a bad blower motor include:


  • Weak airflow


One of the early signs of a bad blower motor is weak airflow. When you notice that your airflow seems weak, it is an indication that your blower motor is faulty. This can happen since the motor can wear out over time, making it difficult for the motor to push as much air through the HVAC system of your car. When this happens, you may notice that the blowers are not as powerful as usual. This problem can also reduce the car defroster’s efficiency since it uses the same fan to blow at the windshield.


  • Unusual noises


When you notice unusual noises that seem to be coming from your HVAC system, it can be one of the signs of a bad blower motor. This can happen since the blower motor of a car is a small rotary motor that operates the fan placed behind your vents. It is the one pushing cold or hot air through the vents at varying speeds, depending on what you choose. This fan is found in a housing in the engine compartment.


Although it is there, it can happen that some foreign object may get sucked into or caught in the blower fan. The blower fan’s blades are made of plastic and they tend to become damaged easily. If they become damaged or are snapped off, you may hear some odd noises coming from behind the vent. The unusual sound may be the blade slapping, or maybe you’ll hear a sudden pop sound or whirring noises that gets louder when the speed of the fan increases. When this happens, then it is a sure sign of a bad blower motor.


  • Smoke or/and unusual smell


When you notice smoke or unusual odors like a burning smell, it can be one of the signs of a bad blower motor. When this happens, you need to slow down and pull over right away since your blower motor is most likely burned. Although a burned blower motor can’t render your car totaled, you’d want to be sure that the smoke coming from your car is not caused by something serious. The smoke or burning smell might have happened due to a short circuit or burned up motor.


However, to be sure, you might want to get under the hood and check if the problem is caused by some other problem. If upon checking, you find out that the fuse in the blower motor circuit is blown, then it means that the circuit was overloaded. If this problem is caused by some electrical issues with the fan or circuit, you can take your car to an auto repair shop with the air turned off. Have the faulty system repaired immediately to prevent any further damage.


  • Blower fan only functions at certain speeds


A bad blower motor can also cause the air from the fan to blow at certain speeds. This can happen but not at all of the speeds, just when you reach a certain speed and the fan will stop to function completely. This should not be the case since most blower motors are designed and built to function at different speeds. This is done to efficiently control or maintain different cabin temperatures. You will know if your blower motor is faulty when it fails to push air at any settings.


This problem can also be caused by some other issues such as a faulty blower motor resistor, bad air door actuator and a few other faulty components. To really determine what caused the weak airflow and get the corresponding repair, it is best to have your car checked by a mechanic.


  • No airflow from the vents


When there is no airflow coming out of the vents when you turn on your heater or air conditioner, it can be one of the signs of a bad blower motor. This can happen when there are short circuits or the blower motor is burned. It won’t be able to function and produce any airflow for the HVAC system. To fix the problem, you will have to replace the faulty blower motor of your car.



Signs of a Bad Blower Motor: How Do You Know If Your Blower Motor is Going Out?



Aside from experiencing any of the signs of a bad blower motor, you can also know if your blower motor is going out by doing some inspections or tests. It is said that when you experience some problems with a part on an electrical circuit, you will have to check the fuse first before doing some other diagnostic tests since a bad fuse can also cause the problem. To do this, do a visual inspection on the fuse. If it is blown, replace the fuse.


If the problem is not the fuse, you can check the wirings. To do this, you need to locate the blower motor. You will usually find it under the dashboard on the passenger side. Look for any signs of damage or loose plugs. If there seems to be no problems with the plugs, check the wirings. You will have to use a wiring diagram and a multimeter to check the wirings.


After checking the wiring and there is no problem with it, you can check the motor itself. You will have to remove the blower motor from your car and check the fan for any debris or other foreign objects that might have stopped it from working. If you see any build up or debris, clean it. You can clean it using an electrical-parts cleaner. You can also oil the bearings. Then check if the blower wheel will spin freely. If doing these things can get your blower motor function again, then good. But if it’s not, you may have to replace your blower motor to get rid of the signs of a bad blower motor.



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