A common symptom of a faulty blower motor resistor is a blower motor that is stuck on one setting. It’s used to control the output speed of the blower motor. I have a dedicated page on how to find electrical shorts if you need more assistance in that area. Another common symptom of a faulty blower motor resistor is a a blower motor that does not function on certain settings. I can’t tell you how often I have found a critter nest in the heater case. For example, in this photo we measured the resistance of this blower motor resistor. Blower motor resistor repair. A resister block will adjust its total resistance as selected by the driver from the switch. If the blower motor doesn't work at all, the blower motor itself must be tested first. 3. OK, these are the test steps: 1 Be careful, on some vehicles when the engine is running the interior fan is in constant operation at a low speed. In most cases, a blower motor resistor fails due to corrosion or … With the amount of current or amps flowing through this circuit, spikes can easily take out the fuse and damage relays. Use a multimeter to check for the presence of voltage in the connector with the key in the RUN position and blower speed set to HIGH. Many blower resistors control current to the blower motor in all speeds except high. Problems with a blower motor resistor are common in many cars. Disconnect the negative and positive power supply. No air from the vehicle’s … Some drivers and car owners might complain about these normal operating conditions. If you check all the fuses and they’re good, the next recommended step is to continue diagnosis by using a test light. This diagram shows how the blower motor resistor is connected in a typical car. Its a good idea to check other like models to determine if there is a problem, or is it just operating as per design intent. Often there are two separate circuit fuses and they can be in separate panels. In most cases, a blower motor resistor fails due to corrosion or overheating. In some cars (e.g. The solution here is to ask an Expert. Press and hold the OFF button and within 10 seconds press and release the Window Defogger button five times. Sometimes, the mechanical resistance to the motor rotation causes an excessive electric current that can overheat and prematurely damage the blower motor resistor. Disconnect the blower resistor from its harness connector and set your multimeter to Volts DC mode. If you need a proper diagnostic procedure, we posted several links where you can access a service manual for your car for a subscription fee. Remember, you need a good ground to complete the circuit. The author of this blog shared his experience of replacing the blower motor resistor in Jeep Liberty. They mount the resister block in the air conditioner or heater case, because of the generous amounts of air flow. Pictured on the right is an interior fan resister assembly from a late 70s GM car or light truck. Cars with an automatic climate control system and vehicles where the blower speed can be adjusted gradually are equipped with an electronic blower motor control module, see the photo. What are the symptoms related to a bad heater blower motor resistor? Paint This: How Long Does Paint Protection Film Last? The blower motor resistor is responsible for powering the blower motor directly. Turn the key to the on position and set the blower speed knob to LO . Your …, Do you have a passion for cars? The blower motor resistor might have to be replaced. Read on to see how Experts have analyzed some common blower motor issues and provided answers to questions. If you do find a burnt fuse continue to test the system and try to find out why it got toasted. This means that the current running through the blower motor, and thus is speed is controlled by the resistor value. He paid $50 to diagnose and $112 to replace the resistor at a local Ford dealership. Unless a fault is correctly diagnosed and resolved, making replacements proves pointless. Remove the screws, and swap out the resistor module. If power is supplied to blower motor through the speed switch and blower motor resistor: Disconnect the electrical connector at the blower motor. Typically it can be activated by pressing and holding different buttons. Testing the voltage at the blower motor. Learn how the rest of the climate control system works and discover why interior fans are an important part of the automotive AC system. In high speed the resistor is bypassed and power is fed to the motor directly from the switch. Another way is to check the voltage at the blower motor, the blower motor control module and other parts of the circuit according to the service manual. There can, of course be other causes, like a faulty blower motor, or a blown fuse, but the two main causes above are far and away the most common. If your test reveals power going into the resister with a solid ground present and nothing coming out, a failed component becomes likely. Your local mechanic or any small repair shop should be able to diagnose the problem. Blower motor resistor wiring repair kit £ 43.80 Excluding vat £ 36.50 This item is currently out of stock but can be back ordered. Blower motor problems can cause many driver complaints. As more resistance is applied to the circuit the slower the interior fan motor will spin. A repair manual can tell you where its location is in your … It will be located between the heater and air conditioning control knobs and the blower motor itself. Nissan and Subaru as well as Chevy and Ford … Please contact us for availability. Test the fuse, with the ignition key on, using the 12-volt test light. Is fixing up …, Over 216 million tires were sold in the United States …, Do you love muscle cars? 7 Awesome Reasons Why You Should Buy a Truck. Honda blower motor control module (power transistor). Blower in car stopped working, took car to dealer, they came back and said it's the resistor for the blower motor. 5 Reasons You Should Invest in One Today, 5 Tips for Smooth Car Maintenance in Winter, Handyman: 10 Updates You Can Make to Your Car on Your Own, Drive With Confidence by Buying the Best All Seasons Tires for Snow, In-Depth Guide to Restoring Muscle Cars for Beginners, 5 Must-Have Qualities When Choosing a Car Repair Shop. This is why at the bottom of the article we include a 2008 F150 blower motor wire diagram. What you should know when buying a used car, How to check the engine when buying a used car, Air fuel ratio (A/F) sensor, how it works, Why a car won't start troubleshooting tips. That's why in some cars, the blower motor may still work in the "High" speed setting if the resistor is bad. As obvious as it may sound, one of the most prominent symptoms that you can be on the lookout for is a lack of... High speeds only. Worn blower motor causes repeat blower motor resistor failure. It's used in cars where the blower motor has only 4 or 5 fixed speeds, as on the left side in this diagram. It's held by two screws. Of course, the quickest way is to make an appointment with your dealer. Adding resistance to the electric circuit reduces the current in the circuit. The bulletin recommends replacing the rear power transistor as a solution. What Does a Flashing Check Engine Light Mean? The diagnostic charts provided in car repair manuals are often very basic and servicing the parts doesn’t require any special tools. On speeds 1-3 the ground is re-routed through the resistor pack and on high speed it bypasses the resistor pack and the motor gets full voltage. The system enters the self-diagnostic mode and at the end of it, if there is a problem, the fault code will be displayed on the display. Reconnect the electrical connector and you’re car heater blower motor is back in business. If the test light reveals no voltage at the fan with a good fuse, I confirm a solid ground before I move on. It's located inside the dash, often on the opposite side of the steering wheel or inside the engine compartment on the firewall. GM called this astro ventilation. BMW calls the blower motor control module a Final Stage Unit and it also is fairly common to fail. Often a visual inspection of the resistor reveals the problem. The service manual advises measuring the voltage at the blower motor, then if not OK, at the power transistor and so on. Next I’ll head to the resister block assembly and check for power coming out of the resister itself. In most modern cars, the blower motor resistor or the control module are installed inside one of the ducts in the HVAC system, close to the blower motor. The blower motor resistor controls the speed of the blower motor indirectly by relaying electrical current to the blower motor control module. Locate the fuse for the blower motor in the owners/service manual. In that case, the blower motor resistor will fail repeatedly. One of the symptoms of a worn out blower motor is that it can intermittently produce a loud screeching noise when running. The blower motor resistor assembly is a common malfunction on them. However, over time, that …, No matter what kind of car you have, they all …, The winter months can be hard on your vehicle. In some GM trucks, a blower motor control module failure can cause the front blower motor to stop working or run after the vehicle has been shut off. In some cars, a failed blower motor resistor can cause a heater fan to stop working completely. Many dealers have the part in stock. A new blower motor resistor will cost you around $20 at the dealer. This happens often in many cars. If it’s in the engine bay you’ll most often find it near the firewall. When the same problem occurred two years later, he ordered the part online for $25 and replaced it himself. Fortunately Volvo changed the layout at the Volvo 700-series (the blower motor was moved to the passenger side of the car, just behind the glovebox), resulting in a much easier way to access the heater motor and resistor for the blower. So effectively, the lower the voltage, the lower the speed. Nevertheless, often when this component fails, it suffers catastrophic heat damage. When up against a blower motor problem always ask an Expert. A failed power transistor was a fairly common cause for not working blower motor in some Honda and Acura vehicles. See these YouTube videos for more info. You’ll have to decide on your own if this is within your skill level. Most of the time, simply replacing the blower motor resistor assembly will take care of the problem. I participate in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. If there is no voltage at the motor, the entire blower motor circuit must be tested, starting from a fuse. The blower is still not working after replacement. The blower motor resistor is the component directly responsible for … The most common symptom of a failed blower motor resistor is when the heater fan only runs at the highest speed setting (4 or 5) and doesn't work at low speeds. The blower motor resistor or control module replacement is not very expensive. The resister block used on many models is coupled with a control module. Check this post, scroll down the page. (The black wire is usually the negative.) The Ford blower motor resistor assembly, covered by this tutorial, has 3 different resistors in series and depending through which resistors the blower motor current is flowing thru' (on its way … How the speed of the blower motor is controlled. In this car, in the highest "4" fan speed setting, the resistor is bypassed and the blower motor is powered directly by the fan switch. In the 2008-2011 Ford Escape, the resistor is located behind the glove box on top of the HVAC unit air duct. For example, in the mentioned 2009 Honda Accord, the + 12V power is supplied directly to the blower motor through the fuse and then through the relay. Oh no! Blower Motor Resistor Testing An A/C blower motor resistor uses resistance to control the speed of the blower motor. If there is a voltage at the motor (at least 4-6 Volt at low speed and 12 Volt at high speed), but the motor doesn't run, the motor is bad or jammed. When I diagnose electrical problems, I start at the load and work my way back through the circuit towards the battery. Using a multimeter set on the Ohm scale, use the positive lead and test the black wire. older GM trucks), a failed blower control module or processor can cause the blower motor to continue running even with the ignition OFF. The way this circuit works is all on the ground side. Things like leaves, twigs, nuts, pieces of a ripped cabin filter can jam the blade of the blower motor. A good indication that you need a blower resistor is if your blower is only working on the highest speed setting. Testing Honda power transistor (blower motor control module). Are Maintenance-Free Batteries Better? Problems with a blower motor control module are less frequent, but it fails for the same reason: due to corrosion or overheating when the motor is jammed or shorted. For example, one of our colleagues had a problem with his 2011 Ford Escape: the fan only worked at the speed 4. That’s why they’re not far from the squirrel cage itself. In some cars, a failed blower motor resistor can cause a heater fan to stop working completely. With that said, failed blower resistor assemblies don't solve all of the possible failures. If a scan tool is not available, in many cars with an automatic climate control system there is a self-testing or diagnostic mode. It's held by two screws and is easy to replace. What is the difference? Finding the location of the fan assembly is a good place to start diagnosis. As more resistance is applied to the circuit the slower the interior fan motor will spin. Don't have a... 2 Disconnect the electrical connector. The motor that runs the fan in the heating and air conditioning system in a car is called a blower motor. When you adjust the fan, the heater blower motor resistor allows the fan to run at several different speeds. I believe General Motors first used it in the 70s. It could also smell like burnt hair. In the long run this could save considerable time and money. This is done, so the resistor or a control module is cooled down by passing air. The blower motor replacement costs from $320 to $650, depending on the car. as a blower motor ages and wears, it can draw more current—more current than the blower motor resistor was designed to handle. The heater blower motor is located behind the glove compartment of your vehicle. I often find DIY car mechanics will skip checking the ground and move right onto parts replacement mode if they find voltage to the fan motors. It took several hours to replace the heater motor and/or resistor. In many cars it's fairly easy; the blower motor is located behind the glove box and held by 3-4 screws. If the resistor isn't replaced for some time after starting to act up, it may fail completely, leaving the entire system useless. This means after replacing the blower motor resistor, check if the blower motor runs freely and doesn't make any noise. The blower motor resistor is responsible for controlling the blower motor speed. Common Problems with Blower Motors. 12 volts is always present at the motor, and the switch in your dash provides the ground. The blower motor control module (Honda calls it Power Transistor) supplies the ground. However, other factors can cause the blower motor resistor to fail prematurely. However, there are a few vehicles out there that make it extremely difficult. …, When you need your automobile to always stay in great …, blower motor problems page for Chrysler and Dodge owners. What Is the Average Cost of a Car Accident? Ford blower motor resistor problems remain the most common solution to interior fan malfunctions on Ford cars and trucks. Two common reasons for this to happen would be drawing too much amperage or a problem with the resister block mentioned above. We have seen instances where a worn-out blower motor causes a recently replaced resistor to fail again. The resister block used on many models is coupled with a control module. The replacement of parts in the blower motor system are some of the easier repairs to perform on the automobile. Repair guide Stage 1 - Investigate. It starts out slow and you figure there is something wrong with resistor, resistor connector (which melted) or the blower motor's old, or they-don't-make-these-blower-motors-like-they-used to. Hyundai owners are often stuck for answers when they are up against blower motor problems. See the photo of a Ford blower motor resistor. Basic instructions on how to troubleshoot the heater blower motor of a Saturn S-series. In newer applicati There are typically two types of blower motor resistors. The user chooses a suitable fan speed by using a selector to connect one of the resistors in the blower resistor pack. Problems with a blower motor resistor are common in many cars. Honda Blower Motor Resistor/Transistor Repair Early 2000 model year Honda Accords, Civics and CR-Vs suffer from a blower motor malfunction where the air conditioning controls will continue to function but the blower motor will not spin, causing no air to come out of you vehicle's vents. If the resistor isn’t working properly, then you’ll experience concerning and inconvenient symptoms in your BMW’s cabin. See, for example, this YouTube videos, add make and model of your vehicle. Diagnostic procedures vary. Went to AutoZone and asked about it. The GM bulletin 06-01-39-002C describes this problem that happens in cold weather. The heater blower motor resistor is an electrical component that is located between your car’s ventilation fan (or blower) and its power source. Anything from no air circulation to annoying or noisy operation. See the photo. You're driving and something on your dashboard catches your eye: a flashing check engine light! Common Problems and Symptoms. If the resistor shows no visual damage, the resistance between terminals must be checked and compared to specifications. As we mentioned earlier, a blower motor resistor isn’t necessary in two instances. Location diagrams will also point out important parts in the climate control system such as relays, switches and fuses. If the resistance is out of specs, the resistor must be replaced. In 2008-2011 Ford Escape / Mazda Tribute, the blower motor resistor is located on top of the HVAC unit air duct behind the glove box. These resistor modules often fail from heat stress that can melt plastic connectors. This is to prevent the circulation of ice-cold air on cold winter days when heat is selected on the climate control. See also: This Ford blower motor resistor has failed due to corrosion, A failed resistor tested with an ohm-meter. You can’t fix what is not broken. At the bottom of this page is a video that’s very popular. Within the blower motor resistor assembly is a non-user serviceable thermal fuse. The current flow is shown in blue and red. The fuse is what usually blows. Fixing your own problems in this system is usually well within the reach of the average do-it-yourself mechanic. The ac blower motor is usually located in the AC duct housing or heater case assembly. As an Amazon Associate I earn from qualifying purchases. Typically it's done by measuring the voltage at the blower motor connector when it's turned on. See 100 other super simple car repairs you can do on your own and avoid a trip to the shop. How Often Do Brake Rotors Need to Be Replaced? You can use the component location diagram in your online service manual to pinpoint the specific location of the squirrel cage (fan blades). Basics Of Troubleshooting The Blower Control Resistor. This can also be caused by a blower motor switch, so a proper diagnosis is highly recommended if you are uncertain of what the issue may be. For example, this happens when the fan blade is jammed by a foreign object or when the motor bearings are worn out and it doesn't spin freely. In others it might be located inside the dash (e;g Mazda 5) which makes replacement difficult. Sometimes it doesn't fail completely, but causes the blower motor to stop working intermittently or run at various speeds. Depending on the year, make, and model you may find this component both in the interior cabin area or outside in the engine compartment side of the firewall. For example, the Honda bulletin 03-048 described a problem where the blower motor for the rear HVAC system in the 2003 Pilot would not work at all speeds. It’s used to control the output speed of the blower motor. The bulletin advises to replace blower motor control module. They always mount the interior fan near the evaporator and heater cores. For example. In this case, the blower motor must also be replaced. If there is a voltage at the motor (at least 4-6 Volt at low speed and 12 Volt at high speed), but the motor doesn't run, the motor is bad. If your heater blower is totally dead, do check your fuses first. Most blower motor problems are resistor related, a problem often overlooked. When the blower motor resistor fails, the air conditioner and heater may still work, but air may blow from the vents at only some of the fan speed settings.. You should see battery voltage (12+). Bookmark this automotive AC blower page or share. You can learn more about this auto repair website over at the Homepage for YouFixCars.com. However, when it comes to the interior fan I will usually go right for the fuse and check that first. No Air. When several resistors are connected in series, the total resistance increases and is equal to the sum of individual resistances. Find out what …, Your car could be a fantastic piece of machinery that has never given you a problem. They often locate these parts in the heater case near the blower motor. Even better an automotive meter to verify good power and grounds at the blower motor. In the 2008-2011 Ford F150 the blower motor resistor is also located behind the glove box, but is installed in the right side of the plastic air duct. For example, this issue was common in older Chrysler and Dodge minivans. The most common symptom of a failed blower motor resistor is when the heater fan only runs at the highest speed setting (4 or 5) and doesn't work at low speeds. This is to provide an ample supply of fresh air in the interior compartment even when no climate control mode is selected. For example, as you can see in this photo, the blower motor resistor in this Ford Escape has failed due to corrosion. Make sure you check the connector side for damage. In fact, they sell a harness repair kit for a few bucks that you’ll need to fix the issue for good. In some older cars, a blower motor resistor was installed on the firewall with the access from under the hood. In most cases when a blower control module fails, the blower motor doesn't work at all. On most American and import cars and light trucks, the blower resistor is located near or on the blower motor. See: how to check a fuse in a car. The service manual describes the testing procedure for each code. More than likely, it will be attached to the ducting near the blower motor so that it is kept cool while it is in use. Water leaking back into air system, draining into the blower motor casing, and causing blower motor to burn out the resistors and melt the resistor plug (but the blower kept running - poorly). Watch these YouTube videos for more info. If a blower motor is bad, it will need to be replaced. Purchase a new resistor module at the auto parts store (usually less than $25). They do this for cooling purposes. The blower resistor is connected in series with the blower fan. Watch the example video below. If so, you’re not alone. What are the symptoms of a bad blower motor resistor? It reviews best practices for diagnosing common electrical problems. The Heater Resistor is … In our case the ohmmeter shows open circuit, which means the resistor has failed. GM calls it Linear Power Module (LPM). A resister block will adjust its total resistance as selected by the driver from the switch. In the past, this was done by varying the voltage supplied to the blower motor. Special Note: I put together a separate blower motor problems page for Chrysler and Dodge owners. A blower motor resistor is a simple electric resistor. The power transistor has 4 wires: two come from the climate control system control unit, one is the ground, one goes to the negative terminal of the blower motor. As an example on GM cars from the 80s and 90s there’s a 20 amp under the dash. Common malfunction on them fail due to corrosion or … start by looking for the blower resistor... 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