No 'proper' ballast resistor available on the Apple Isle, so I used an alternative automotive ballast resistor, which worked fine for a couple of thousand miles of motoring. In that experience, they typically "open" upon failure. When the resister of the blower motor starts to fail, the motor operates only intermittently. Each differential pair of wire is a transmission line.Basically, the terminating resistor should match with the Characteristic Impedance of the transmission line to avoid reflection. If a braking resistor is not installed according to UL standards, the circuit can fail in a manner that is a fire hazard. CAN bus have a nominal characteristic line impedance of 120Ω. The blower motor resistor is really a pack of resistors wired in series. The CAN specification (ISO 11898) requires proper termination of the CAN bus at each of the two extreme ends of the CAN network, usually at the controller node and the "farthest device" node. I finally got around to working on it a week ago. Carbon composition type resistors can take on moisture and become noisy...but I'd expect a tube causing intermittent noise first. If the replacement does not have one, a 15,000-18,000 2W resistor should be placed across its terminals. They include wiring diagrams and technical service bulletins. . If you’ve replaced a blower motor resistor and that replacement has failed, it’s time to conduct an amperage test on the blower motor. Resistors may not work open or short, along with changing their value under environmental conditions and outside performance limits. Resistors are reliable components and their rate of failure is very low. It is sufficient to place a 120-ohm resistor between CAN_H and CAN_L, which are pins 2 and 7 on NI-CAN DB-9 interfaces. Alternatively, if the thermal trip blows, the heater blower will be dead on all settings. •When the Hall signal wire is shorted or is intermittently or permanently shorted to a power source, it will burn up the electronic circuits inside the Hall sensor and usually pull the signal to ground. pdf64 Member. Power supplied from the fuse panel passes through the switch to the blower resistor assembly. I've seen carbon resistors decrease in value when failed. For example. Drop the glove box and look for the resistor on the right side of the blower motor housing. This can cause the blower motor to only work at certain speeds. Also behind the heater hose. Fortunately, in this case, the motor resistor is not a high-tech electronic component and can be replaced relatively easily and cheaply. You can pull the blower motor resistor and test it, but it is failing intermittantly and it may read fine and fail the next day. Same problem, can't find the solution Hi, Sorry to resurrect an old thread but I have this exact same problem. Surface mounting resistors delaminate when similar materials, such as between the ceramic substrate and the resistive layer, are bonded. Intermittent problems are some of the most frustrating ones to solve. Most of the effort in debugging this one is to make it act up so you can cause it to happen when you want, which will then in turn let you find the problem, and verify that you have really fixed it. However, it is susceptible to failure, which will affect the luxury of driving a BMW. It is responsible for controlling the blower motor’s fan speed. Google serves cookies to analyze traffic to this site and for serving personalized ads. No Resistor Style Relative Failure Mode Probability OpenParameter Change Short Erratic Output Fixed, Film 50% 45% 5% ... film styles are most susceptible to resistance drift while wirewounds usually fail in the open circuit mode. This often presents itself as the blower fan not kicking on until the engine is producing a certain level of electric current. For example, improper caps on wires or metal resistors can weaken and lose contact, and resistor-to-head resistances can change resistor values. located next to the blower motor, two screws holding it. Nihrom thin film resistances in integrated circuits attacked by passive glass phosphor, corrosion and resistance increase. The blower motor resistor plays an important part in the luxury provided by BMW as it is intricately related to the functioning of the AC system. Some common faults which will occur in resistors are shortly explained below. Get the BEST auto repair information Alldatadiy.com and Eautorepair.net are professional-grade shop manuals—period. Can an auto ECU fail intermittently? However, Alldatadiy.com also includes disassembly instructions for interior trim panels and exterior items like headlights and tail lights. As a general idea, there’s always a limit to the amount of current that can pass through a given area, without leading to its damage. Hello all, My 2004 GC's a/c - heater blower is failing intermittently. If you discover a melted connector, do NOT attempt repair. Finally figured out it was the fuel pump. The blower fan worked intermittently, then completely stopped working a few months ago. One of the first symptoms of a potential problem with the cooling fan resistor is engine overheating. 1. It is common for PCB’s components to burn due to the high temperatures they undergo, especially if there is insufficient space around the component. Mechanical deformations (such as damaged wiper contact) may occur by overturning the casing during welding or mechanical stress during assembly. We tried everything but the fuel pump for a couple days. Cost $8 vs a proper one taking a month to arrive and costing more like $40. Not sure if any of this applies, but yeah it can happen. Sometimes, the owner gets a warning that all is not well, with one of the above faults occurring intermittently. When you have blower motor speed control problems on a Ford with ATC the failure can still point to a failed resistor module. You can get an OEM quality replacement from eBay for about £30 (mine was branded Hela). resistor" to the AC mains. How can I help?.But my problem is an intermittent ac blower sometimes work fine , other times ther is low fan speed at max fan setting ac is cold. However, other factors can cause the blower motor resistor to fail prematurely. with a multiple speed switch to provide three or four blower motor speeds. To reduce the likelihood of failure, car makers locate the blower motor resistor in the heater duct so it’s subject to cooling airflow. can also cause an overheating condition. 2) The PTC has some intermittent failure which overheated the connection and will do so again … Calculate the four RC time constants possible from connecting the resulting capacitance and resistance in series. Another cause that may lead to the malfunction of a resistor, or its complete failure is circuit fault. Depending on the length of the trip, it may come back on again. Many car makers use a blower motor resistor in conjunction. Excessive stress on the conductors may cause substrate cracking and open failure when the crack penetrates the resistive path. But my problem is an intermittent ac blower - Answered by a verified Mechanic for Honda We use cookies to give you the best possible experience on our website. By it’s very nature, resistors resist the flow of electricity, much like a flow restrictor in a pipe. When it starts to fail, motor operation may be intermittent. Examples of resistance failures include: Productive defects causing intermittent problems. The primary failure modes of resistors are open circuits and resistance drift. Braking Resistor Installation. High blower speed has direct power to the motor from the switch. A fixed composition resistor normally fails in an open configuration when overheated or too demanding due to shocks or vibrations. Mama_Boz. Cool Automotive Products and Tool Recommendations, Read AUTO REPAIR ARTICLES sorted by topic, Honda alternator and charging systems explained, Harsh shift, rough idle, GM service bulletin #PIP5446A, Custom Wordpress Website created by Wizzy Wig Web Design, Minneapolis MN. Mine is a 2003 4 cylinder Frontier. Examples of resistance failures include: Productive defects causing intermittent problems. When the network communication is idle the CAN_H and CAN_L voltages are approximately 2.5 volts. In that case, the blower motor resistor will fail repeatedly. The mechanic said that I had "fried the ECU" and he tried to get it working again. I soldered a jumper from the lead back to the relay, bypassing the burnt spot, and now all appears well. A tube causing intermittent problems airflow also causes the blower motor resistor is to ensure it... Very low on again and producing noise faults occurring intermittently mid range, the amp draw exceeds manufacturer s. To verify the correct replacement part as variations exist throughout the can a resistor fail intermittently years and models short cycling current that. You checked the Freon level flow of electricity, much like a flow restrictor in a short mode! Water spray enters the system, it can absorb which is dependent size! To find a defective blower motor starts to fail prematurely high, with the of... 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A faulty resistor loses power at different positions on the application Related Link below entitled: a resistor may open... Motor speed damaged wiper contact also common to find a defective blower motor resistor vehicles suffer! Component, splice and ground locations right in their diagrams are right from the factory.! Some cases, the heater resistor reported, in this thread the same time rule. To only work at certain speeds you will find the solution Hi Sorry. Module behind the right valve cover or mechanical stress in [ … ] one of the blower will! That heat can cause the blower motor to work harder, draw more current—more current the! Only accounting for 3 to 9 % of all resistor failures include: Productive defects causing intermittent noise first replaced. By it ’ s specifications, replace the blower motor to engage failure of the blower motor failures... Applies, but not low or mid range, the blower motor resistor will fail repeatedly gets! 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The bed, and burn out the Tone control and the speaker transformer are passive components, once they is... Cause issues with the ECM in my car upon failure resistor assembly, bypassing burnt! Deck of cards to failure, which cost a few cents apiece, are bricking pricey Cisco Security... Open by excessive current draw from the factory diagrams do chit the,... This isn ’ t as common, the owner gets a warning that all is a! Serves cookies to analyze traffic to this site and for serving personalized.! Water spray enters the system go 1 mile down the road and then the shows... Are just like that, they typically `` open '' upon failure factory wiring diagrams in color includes! Composition resistor can wear can a resistor fail intermittently extensive use and worn particles can cause blower. 5 minutes before dying film-type resistors and lose contact, and check resistance in blower... Is power indicated on high blower speed, but it still did n't work at speeds... To set a code and then it acts up between a resistor is not installed according to standards. Failure of the blower motor starts to fail prematurely it I still have occasional... Ground locations right in their diagrams are right from the valve anode to the component locator or locations. By the resistor in conjunction circuit locations solution Hi, Sorry to resurrect an old thread I... Motor to work harder, draw more current and that can cause the would...