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What is a Blower Motor Resistor and How do You know if it is Working?

What is a Blower Motor Resistor and How do You know if it is Working

The air conditioner is one of the most important extras a person’s car can have. It keeps you cool when cruising around on hot days and it helps to keep your ice cream from melting as you drive home from the store. When it goes out, you and your passengers might be awfully uncomfortable.

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Your air conditioner is made up of many parts. The motor that operates the fan in the air conditioning setup is known as a blower motor. It may be located in one of several places depending on the make and model of your car. The resistor is one of the parts of the blower motor. the resistor dictates the speed of the blower motor. 


There are two different kinds of resistors a blower motor resistor and an electronic blower motor control module.  A regular blower motor resistor is employed when the blower motor has only 4 or 5 fixed speeds. Vehicles with an automatic climate control system or those that allow the blower speed to be adjusted gradually come equipped with an electronic blower motor control module.


In the vast majority of contemporary automobiles, you will find the blower motor resistor or the control module inside the ducts in the HVAC, near the blower motor. The reason for this is so that the control module can be cooled down by the passing air. In earlier days, a blower motor resistor was installed on the firewall that you had to access from under the hood. 


Problems that May Occur with the Blower Motor Resistor 

Issues with a blower motor resistor happen often. The most typical symptom of a non-working blower motor resistor is when the heater fan only operates at the highest speed setting and will not work at any other speed. There are certain vehicles in which a failed blower motor resistor can result in a heater fan to stop operating entirely.


Normally, a blower motor resistor will stop working because of corrosion or overheating. The mechanical resistance to the motor rotation creates an excessive electrical current that might overheat and harm the blower motor resistor. One example of this would be when the fan blade has a foreign object in it, or when the motor bearings can’t spin properly because they are worn down.


Occasionally you may have issues with a blower motor control module. Although this happens less often, it occurs for the same reason. due to corrosion or overheating when the motor is shortened or has a foreign object in it. 


Generally, when a blower control module stops working, the blower motor won’t work. There are older cars in which, a failed blower control module or processor can make the blower motor run when the ignition is off.


How to diagnose a BMR

There are several different kinds of diagnostic procedures. Usually, you can find the problem by simply doing a visual inspection of the resistor. For example, a resistor may fail due to corrosion that you can see. If you cannot see the damage, you should check the resistance between terminals. Your owner’s manual should tell you how many ohms your resister should read. If the resistance falls outside of those specs, the resistor is going to have to be replaced.


Occasionally, a blower motor resistor fails because of issues with the blower motor itself. You should check to make sure that the blower motor runs and doesn't make any noise. There are some cases in which a spent blower motor might cause a new resistor to fail. If this happens, the blower motor must be replaced. A worn-out blower motor may make a screeching noise when it is running.


How do you test a blower motor?

When the blower motor does not work, you can test it. This is done by measuring the voltage at the blower motor connector. You will have to turn off the unit to do this. If the voltage at the motor reads 4-6 Volts at low speed and 12 Volts at high speed, and the motor is not running, the motor is probably jammed or it may just be worn out.


Things like gravel, twigs, and portions of a torn cabin filter can get into the blade of the blower motor. This is a very common occurrence. When there isn’t any voltage to the motor, you should test the whole blower motor circuit. The first thing you will do is check a fuse.


How to Check a Fuse in a Car

A fuse is a low-resistance resistor component that prevents a circuit from becoming overloaded. It’s a small piece of wire that will melt when exposed to excessive electrical current. A fuse is attached in series to the circuit it shields. When a fuse is blown, it can cause an electrical short or create an overloaded circuit. 


You will find the fuse box is located in your vehicle. There are some automobiles that have multiple fuse boxes with multiple fuses. Whenever something electrical in your vehicle suddenly stops working, you always want to check the fuse box.


Equipment You Will Need

You will need a flashlight, needle-nosed pliers, and a test light in order to get started. 


Step 1

Your car is likely to have more than one fuse box, so make sure to consult your owner’s manual to locate the one that corresponds to your blower motor. 


Fuse boxes will generally be located under the hood, under the dashboard, under the back seat, or in the trunk. 


Once you locate the fuse you will want to remove it. Remember, whenever you work on your car it should be turned off.  You can take it out with the fuse puller you will find in the fuse box, or with your pliers.


Step 2 

Examine the fuse for any cracks or damages. You will need your flashlight for this. If it is damaged it needs to be replaced.


Part 3

Even if you cannot find the appropriate fuse in the box, you can still perform a test to see if they are bad. You will want to turn the ignition into one or two positions. The test light will have a clip on it. You want to attach that clip to bare metal in the car. Touch your pliers to the test light of each fuse. If the fuse lights up on both sides, it is good, if it does not, it needs to be replaced.


Part 4

You will then want to replace the fuse with a brand new one. You can go to the dealership for your fuse, but if you want to save a buck or two, you can get them at the hardware store. 


If there is not a blown fuse, you will want to test the blower motor itself. There are a few simple steps you can take to accomplish this.

Most cars with an automatic climate control system have a self-testing or diagnostic mode. You may be able to activate it by pressing and holding various buttons. Your owner’s manual should guide you through the process of testing it. A Mechanic can diagnose the HVAC system with a scan tool. 

If a blower motor is bad, you must replace it if you want your HVAC system to work properly. The blower motor will cost anywhere from $150 to $2,000 to replace. The cost varies so much because of the location of the component. It all depends on the make and the model of your car. You will have a few options for getting the repairs done.

Taking Your Car to an Auto Body Shop

Most people in the U.S. prefer to take their vehicles to an auto body shop when they need repairs. You will get to talk to the mechanic directly and you will pay less money than if you take your vehicle to the dealership. 

You can find a body shop in your area on the AAA website. In the case of a blower motor or blower motor rectifier, you will definitely want to find a body shop that specializes in your make and model of car. Ask what kind of certification the mechanics have and when they were certified. 

Taking Your Car to the Dealership 

You can always take your car to the dealership for repairs. Although it is quite a bit more expensive, it might not be such a bad idea in this case. Blower motors vary from car to car and it is helpful to have a mechanic who is an expert in your make and model of automobile. 

The dealership will have all of the necessary parts on hand and they will be able to do the repairs right away. They will charge you by the job and not by the hours, so you do not have to worry about the mechanic dragging their feet to get more money.

If the cost of the repairs exceeds the value of your vehicle or if your car is just old, you may want to consider replacing it. If you do get a new car, you will have a few options for capitalizing on the old one. 

Use Your Car as a Trade-In


When you buy your new vehicle, the salesperson will offer you a trade-in allowance for your old car. They are likely to not offer you very much money. They will rely on your being too lazy and stressed to get other offers on your car. You should call junk yards first and let the salesman at the dealership know that you have done your homework. 


The salesperson may then offer you what seems like a very good price for your junk car. When they do this, be sure to read every line of the new car offer carefully. They may try to tack the money they gave you for a trade-in right back onto the final price of the new vehicle. It is best not to tell them that you have a car to trade in until you get a final offer.


Sell Your Car Online

If you Google, “car sales”  Many websites will come up. These car sales sites will allow you to list your vehicle for a monthly fee. They often offer packages that are good for several months. The reason they give you such long term listing options is that it can take many months to sell your car. There are a lot of scams out there and buyers don’t trust these sites.


When a  prospective buyer does call, you will have to make time to show them the vehicle. They may take their time about looking at it, tell you they will think about it and decide not to buy it. You may have to show your ride several times before selling it.  The people who by cars on such sites are often mechanics who may only be interested in purchasing a part or two. This will leave you with a parted out car on your property that will eventually need to be towed.

Sell Your Car to Us

Cash Cars Buyers is absolutely the best option for selling your used or junk car. Our process is easy. You just fill out a form. We will ask you for your name, email address, and phone number. We will also ask for your make, model, VIN number, mileage, and year of the car. 


Once we receive your information, we will call you back and offer you the best price we can. If you accept our offer, we will make arrangements to come and get your vehicle. We will arrive on time, pay you in cash, and tow the old clunker to our yard for free. We pay as much as $500 for junk cars, so be sure to contact us today.

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