No air from the vehicle’s … If a blower motor is bad, it will need to be replaced. Sometimes, a blower motor resistor might fail due to problems with the blower motor itself. The service manual describes the testing procedure for each code. The current flow is shown in blue and red. Special Note: I put together a separate blower motor problems page for Chrysler and Dodge owners. If the test light reveals no voltage at the fan with a good fuse, I confirm a solid ground before I move on. The bulletin advises to replace blower motor control module. as a blower motor ages and wears, it can draw more current—more current than the blower motor resistor was designed to handle. Typically it can be activated by pressing and holding different buttons. 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. In most cases, a blower motor resistor fails due to corrosion or … Diagnostic procedures vary. If your heater blower is totally dead, do check your fuses first. Don't have a... 2 I believe General Motors first used it in the 70s. A failed power transistor was a fairly common cause for not working blower motor in some Honda and Acura vehicles. It's located inside the dash, often on the opposite side of the steering wheel or inside the engine compartment on the firewall. The bulletin recommends replacing the rear power transistor as a solution. BMW calls the blower motor control module a Final Stage Unit and it also is fairly common to fail. On vehicles with early climate control systems the fans may not activate until the engine reaches a specific temperature. The resister block used on many models is coupled with a control module. Anything from no air circulation to annoying or noisy operation. A good indication that you need a blower resistor is if your blower is only working on the highest speed setting. Blower motor resistor repair. You can’t fix what is not broken. What are the symptoms of a bad blower motor resistor? It's used in cars where the blower motor has only 4 or 5 fixed speeds, as on the left side in this diagram. Basics Of Troubleshooting The Blower Control Resistor. Hyundai owners are often stuck for answers when they are up against blower motor problems. The blower motor resistor might have to be replaced. Honda blower motor control module (power transistor). The ac blower motor is usually located in the AC duct housing or heater case assembly. If the blower motor doesn't work at all, the blower motor itself must be tested first. Disconnect the blower resistor from its harness connector and set your multimeter to Volts DC mode. 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. They often locate these parts in the heater case near the blower motor. What are the symptoms related to a bad heater blower motor resistor? If power is supplied to blower motor through the speed switch and blower motor resistor: Disconnect the electrical connector at the blower motor. We have seen instances where a worn-out blower motor causes a recently replaced resistor to fail again. GM calls it Linear Power Module (LPM). 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. The blower motor control module (Honda calls it Power Transistor) supplies the ground. If the blower motor resistors’ internal components fail it may cause the blower motor to malfunction, or not function at all on one or more of the settings. 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. 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. As an Amazon Associate I earn from qualifying purchases. Location diagrams will also point out important parts in the climate control system such as relays, switches and fuses. There are typically two types of blower motor resistors. Blower in car stopped working, took car to dealer, they came back and said it's the resistor for the blower motor. What Is the Average Cost of a Car Accident? For example, one of our colleagues had a problem with his 2011 Ford Escape: the fan only worked at the speed 4. Learn how the rest of the climate control system works and discover why interior fans are an important part of the automotive AC system. It could also smell like burnt hair. 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. A new blower motor resistor will cost you around $20 at the dealer. That's why in some cars, the blower motor may still work in the "High" speed setting if the resistor is bad. It’s used to control the output speed of the blower motor. One of the symptoms of a worn out blower motor is that it can intermittently produce a loud screeching noise when running. Adding resistance to the electric circuit reduces the current in the circuit. 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. Watch the example video below. 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. The blower motor resistor controls the speed of the blower motor indirectly by relaying electrical current to the blower motor control module. 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. 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. Blower motor problems can cause many driver complaints. According to the service manual, it must be around 4-5 ohms. Watch these YouTube videos for more info. This means that the current running through the blower motor, and thus is speed is controlled by the resistor value. In many cars it's fairly easy; the blower motor is located behind the glove box and held by 3-4 screws. In our case the ohmmeter shows open circuit, which means the resistor has failed. The user chooses a suitable fan speed by using a selector to connect one of the resistors in the blower resistor pack. In newer applicati They do this for cooling purposes. 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. However, other factors can cause the blower motor resistor to fail prematurely. 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. A common symptom of a faulty blower motor resistor is a blower motor that is stuck on one setting. These resistor modules often fail from heat stress that can melt plastic connectors. A resister block will adjust its total resistance as selected by the driver from the switch. Reconnect the electrical connector and you’re car heater blower motor is back in business. In the long run this could save considerable time and money. 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. Paint This: How Long Does Paint Protection Film Last? Remember, you need a good ground to complete the circuit. If it’s in the engine bay you’ll most often find it near the firewall. Problems with a blower motor resistor are common in many cars. 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.. For example, as you can see in this photo, the blower motor resistor in this Ford Escape has failed due to corrosion. He paid $50 to diagnose and $112 to replace the resistor at a local Ford dealership. On most American and import cars and light trucks, the blower resistor is located near or on the blower motor. 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. Start by looking for the blower fan resistor. The author of this blog shared his experience of replacing the blower motor resistor in Jeep Liberty. For example, in this photo we measured the resistance of this blower motor resistor. Repair guide Stage 1 - Investigate. If you check all the fuses and they’re good, the next recommended step is to continue diagnosis by using a test light. In this diagram, the fan switch is set to the speed "1", so the blower motor current is reduced by three resistors (R2 + R3 + R4) connected in series. Problems with a blower motor resistor are common in many cars. Find out what …, Your car could be a fantastic piece of machinery that has never given you a problem. 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. See 100 other super simple car repairs you can do on your own and avoid a trip to the shop. However, when it comes to the interior fan I will usually go right for the fuse and check that first. 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. However, over time, that …, No matter what kind of car you have, they all …, The winter months can be hard on your vehicle. However, there are a few vehicles out there that make it extremely difficult. The resister block used on many models is coupled with a control module. Disconnect the Heater Blower Resistor from … 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. So effectively, the lower the voltage, the lower the speed. Next I’ll head to the resister block assembly and check for power coming out of the resister itself. There’s also a 30 amp Maxi fuse in the engine bay convenience center. If you do find a burnt fuse continue to test the system and try to find out why it got toasted. The blower motor resistor is responsible for controlling the blower motor speed. 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. You can learn more about this auto repair website over at the Homepage for YouFixCars.com. If the resistor isn’t working properly, then you’ll experience concerning and inconvenient symptoms in your BMW’s cabin. 12 volts is always present at the motor, and the switch in your dash provides the ground. A repair manual can tell you where its location is in your … 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. You should see battery voltage (12+). 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. 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. 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 … A resister block will adjust its total resistance as selected by the driver from the switch. …, When you need your automobile to always stay in great …, blower motor problems page for Chrysler and Dodge owners. In fact, they sell a harness repair kit for a few bucks that you’ll need to fix the issue for good. The way this circuit works is all on the ground side. What Does a Flashing Check Engine Light Mean? It's held by two screws and is easy to replace. 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. This means after replacing the blower motor resistor, check if the blower motor runs freely and doesn't make any noise. Went to AutoZone and asked about it. In most cases when a blower control module fails, the blower motor doesn't work at all. Fix your heater blower resistor problems from £2.99 Over the last ten years or so, motor manufacturers have introduced more sophisticated Heater Blower Resistors to control the blower fan motor for the heater and, on many, the digital aircon too. Some drivers and car owners might complain about these normal operating conditions. older GM trucks), a failed blower control module or processor can cause the blower motor to continue running even with the ignition OFF. See also: This Ford blower motor resistor has failed due to corrosion, A failed resistor tested with an ohm-meter. See these YouTube videos for more info. As more resistance is applied to the circuit the slower the interior fan motor will spin. As an example on GM cars from the 80s and 90s there’s a 20 amp under the dash. If the resistance is out of specs, the resistor must be replaced. Within the blower motor resistor assembly is a non-user serviceable thermal fuse. Attach the clip lead of the test light to a good ground like a bolt screwed into metal, and touch the sharp probe end to the terminals on the fuse. Typically it's done by measuring the voltage at the blower motor connector when it's turned on. Two common reasons for this to happen would be drawing too much amperage or a problem with the resister block mentioned above. They mount the resister block in the air conditioner or heater case, because of the generous amounts of air flow. (The black wire is usually the negative.) In others it might be located inside the dash (e;g Mazda 5) which makes replacement difficult. The blower is still not working after replacement. In some cars, a failed blower motor resistor can cause a heater fan to stop working completely. Press and hold the OFF button and within 10 seconds press and release the Window Defogger button five times. Pictured on the right is an interior fan resister assembly from a late 70s GM car or light truck. You’ll have to decide on your own if this is within your skill level. Mechanics at a dealership can diagnose the HVAC system with a scan tool. This is why at the bottom of the article we include a 2008 F150 blower motor wire diagram. It took several hours to replace the heater motor and/or resistor. Things like leaves, twigs, nuts, pieces of a ripped cabin filter can jam the blade of the blower motor. The blower motor replacement costs from $320 to $650, depending on the car. The GM bulletin 06-01-39-002C describes this problem that happens in cold weather. Worn blower motor causes repeat blower motor resistor failure. Sometimes it doesn't fail completely, but causes the blower motor to stop working intermittently or run at various speeds. This is to prevent the circulation of ice-cold air on cold winter days when heat is selected on the climate control. It reviews best practices for diagnosing common electrical problems. Many dealers have the part in stock. 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). Blower motor resistor wiring repair kit £ 43.80 Excluding vat £ 36.50 This item is currently out of stock but can be back ordered. If the resistor shows no visual damage, the resistance between terminals must be checked and compared to specifications. Is fixing up …, Over 216 million tires were sold in the United States …, Do you love muscle cars? Using a multimeter set on the Ohm scale, use the positive lead and test the black wire. In the setting "2", there are two resistors connected in series, and in "3", there is only one resistor. In that case, the blower motor resistor will fail repeatedly. With the amount of current or amps flowing through this circuit, spikes can easily take out the fuse and damage relays. The solution here is to ask an Expert. In some older cars and trucks the blower motor resistor is installed on the firewall, with the access from under the hood. Many blower resistors control current to the blower motor in all speeds except high. The blower motor resistor or control module replacement is not very expensive. Of course, the quickest way is to make an appointment with your dealer. This diagram shows how the blower motor resistor is connected in a typical car. 3. Nevertheless, often when this component fails, it suffers catastrophic heat damage. OK, these are the test steps: 1 Your local mechanic or any small repair shop should be able to diagnose the problem. Testing the voltage at the blower motor. When up against a blower motor problem always ask an Expert. With that said, failed blower resistor assemblies don't solve all of the possible failures. Common Problems and Symptoms. The blower resistor is connected in series with the blower fan. They always mount the interior fan near the evaporator and heater cores. Step 1. 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. Be careful, on some vehicles when the engine is running the interior fan is in constant operation at a low speed. Oh no! The motor that runs the fan in the heating and air conditioning system in a car is called a blower motor. See: how to check a fuse in a car. Fixing your own problems in this system is usually well within the reach of the average do-it-yourself mechanic. The fuse is what usually blows. For example. Nissan and Subaru as well as Chevy and Ford … A blower motor resistor or a blower motor control module is the part that controls the speed of the blower motor. 7 Awesome Reasons Why You Should Buy a Truck. The diagnostic charts provided in car repair manuals are often very basic and servicing the parts doesn’t require any special tools. This happens often in many cars. 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. When several resistors are connected in series, the total resistance increases and is equal to the sum of individual resistances. Unless a fault is correctly diagnosed and resolved, making replacements proves pointless. In this case, the blower motor must also be replaced. How the speed of the blower motor is controlled. Most of the time, simply replacing the blower motor resistor assembly will take care of the problem. The heater blower motor is located behind the glove compartment of your vehicle. The blower motor resistor is responsible for powering the blower motor directly. The blower motor resistor assembly is a common malfunction on them. I also have a page focused on four GM HVAC issues on cars and trucks from the 2000s. If the resistor isn't replaced for some time after starting to act up, it may fail completely, leaving the entire system useless. Purchase a new resistor module at the auto parts store (usually less than $25). Bookmark this automotive AC blower page or share. In some cars, a failed blower motor resistor can cause a heater fan to stop working completely. 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. 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. In the past, this was done by varying the voltage supplied to the blower motor. See, for example, this YouTube videos, add make and model of your vehicle. Most blower motor problems are resistor related, a problem often overlooked. It’s used to control the output speed of the blower motor. If a scan tool is not available, in many cars with an automatic climate control system there is a self-testing or diagnostic mode. The Heater Resistor is … Testing Honda power transistor (blower motor control module). You're driving and something on your dashboard catches your eye: a flashing check engine light! The service manual advises measuring the voltage at the blower motor, then if not OK, at the power transistor and so on. Disconnect the negative and positive power supply. 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. 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. Even better an automotive meter to verify good power and grounds at the blower motor. Read on to see how Experts have analyzed some common blower motor issues and provided answers to questions. When the same problem occurred two years later, he ordered the part online for $25 and replaced it himself. Common Problems with Blower Motors. Locate the fuse for the blower motor in the owners/service manual. Are Maintenance-Free Batteries Better? As we mentioned earlier, a blower motor resistor isn’t necessary in two instances. 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. Your …, Do you have a passion for cars? No Air. It will be located between the heater and air conditioning control knobs and the blower motor itself. In high speed the resistor is bypassed and power is fed to the motor directly from the switch. When I diagnose electrical problems, I start at the load and work my way back through the circuit towards the battery. It's held by two screws. When you adjust the fan, the heater blower motor resistor allows the fan to run at several different speeds. 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. 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. As more resistance is applied to the circuit the slower the interior fan motor will spin. Disconnect the electrical connector. This is done, so the resistor or a control module is cooled down by passing air. Sometimes, the mechanical resistance to the motor rotation causes an excessive electric current that can overheat and prematurely damage the blower motor resistor. Remove the screws, and swap out the resistor module. 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. 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. In most cases, a blower motor resistor fails due to corrosion or overheating. GM called this astro ventilation. For example, in the 2009 Honda Accord, the service manual describes the procedure as follows: Turn the ignition to ON. Test the fuse, with the ignition key on, using the 12-volt test light. Ordered a new one and replaced it. Finding the location of the fan assembly is a good place to start diagnosis. Ford blower motor resistor problems remain the most common solution to interior fan malfunctions on Ford cars and trucks. Check this post, scroll down the page. I can’t tell you how often I have found a critter nest in the heater case. If so, you’re not alone. Often a visual inspection of the resistor reveals the problem. Make sure you check the connector side for damage. The blower motor resistor can usually be found under the dash as well. If your test reveals power going into the resister with a solid ground present and nothing coming out, a failed component becomes likely. This is to provide an ample supply of fresh air in the interior compartment even when no climate control mode is selected. How Often Do Brake Rotors Need to Be Replaced? If there is no voltage at the motor, the entire blower motor circuit must be tested, starting from a fuse. Often there are two separate circuit fuses and they can be in separate panels. This thread at f150online.com shows where the resistor is located. Blower Motor Resistor Testing An A/C blower motor resistor uses resistance to control the speed of the blower motor. See the photo of a Ford blower motor resistor. What is the difference? The blower motor resistor is the component directly responsible for … Basic instructions on how to troubleshoot the heater blower motor of a Saturn S-series. You can use the component location diagram in your online service manual to pinpoint the specific location of the squirrel cage (fan blades). In the 2008-2011 Ford Escape, the resistor is located behind the glove box on top of the HVAC unit air duct. A blower motor resistor is a simple electric resistor. This means when you remove the part you will instantly see that it has melted spots. In some cars (e.g. The heater blower motor resistor is an electrical component that is located between your car’s ventilation fan (or blower) and its power source. In some older cars, a blower motor resistor was installed on the firewall with the access from under the hood. At the bottom of this page is a video that’s very popular. 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. See the photo. That’s why they’re not far from the squirrel cage itself. For example, this issue was common in older Chrysler and Dodge minivans. Please contact us for availability. The replacement of parts in the blower motor system are some of the easier repairs to perform on the automobile. Turn the key to the on position and set the blower speed knob to LO . Working intermittently or run at several different speeds in high speed the for., blower motor in all speeds except high Escape, the blower motor that does not function on certain.! Dash provides the ground causes a recently replaced resistor to fail again the engine is running interior! 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