buddy Posted August 8, 2010 Share Posted August 8, 2010 where can i get a blower motor resistor for a 87 superliner. dealer says no got! man I have a lot of trouble trying to get the simple things for this truck Quote Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/ Share on other sites More sharing options...
HK Trucking Posted August 8, 2010 Share Posted August 8, 2010 Just run the blower on "hi" all the time, no resistor needed. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61203 Share on other sites More sharing options...
rhasler Posted August 8, 2010 Share Posted August 8, 2010 where can i get a blower motor resistor for a 87 superliner. dealer says no got! man I have a lot of trouble trying to get the simple things for this truck The resistor part number for the RW in this post: http://www.bigmacktrucks.com/index.php?showtopic=15191 is 4379-RD536470 (or at least it used to be). It was built in 1987, so I would imagine it should be the same as yours. I'll try to check on it tomorrow and see if it available or if they're just blowing smoke. Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61206 Share on other sites More sharing options...
ThaddeusW Posted August 8, 2010 Share Posted August 8, 2010 Sounds like quite a large resistor. How many amps is a blower motor? you could size up a resistor from an electronics supply catalog. I have a few large ones lying around but they are rated for 200 watts only, and those are actually huge. Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61212 Share on other sites More sharing options...
Rob Posted August 8, 2010 Share Posted August 8, 2010 Sounds like quite a large resistor. How many amps is a blower motor? you could size up a resistor from an electronics supply catalog. I have a few large ones lying around but they are rated for 200 watts only, and those are actually huge.Not really too physically large. They depend on airflow through the plenum to survive. Leaves and trash buildup on the cowl inlet screens take them out quickly due to reduced airflow. As Herv stated if the blower motor is run on the "high" position of the switch, the resistor is bypassed electrically and not in the circuit.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61219 Share on other sites More sharing options...
theakerstwo Posted August 9, 2010 Share Posted August 9, 2010 I am thinking a FLD freightliner may use the same one. If it ant you could rework the mount and it would. The FLD has 4 ter. on it. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61226 Share on other sites More sharing options...
buddy Posted August 9, 2010 Author Share Posted August 9, 2010 I am thinking a FLD freightliner may use the same one. If it ant you could rework the mount and it would. The FLD has 4 ter. on it.I am going to take a pic of it and go to freightliner cause i think you is rightThanks RichPS high speed does not work with this resister. Quote Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61287 Share on other sites More sharing options...
rhasler Posted August 9, 2010 Share Posted August 9, 2010 Hey Dunny, I had a parts man check that number out, it's still a good number and it's available (literally hundreds in Mack's warehouses). He told me probably around $5.00 Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61288 Share on other sites More sharing options...
buddy Posted August 9, 2010 Author Share Posted August 9, 2010 Hey Dunny, I had a parts man check that number out, it's still a good number and it's available (literally hundreds in Mack's warehouses). He told me probably around $5.00i only have 1 mack dealer here. How would i go about getting it cause my dealer says that mack does not stock it anymore Quote Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61290 Share on other sites More sharing options...
hatcity Posted August 9, 2010 Share Posted August 9, 2010 i only have 1 mack dealer here. How would i go about getting it cause my dealer says that mack does not stock it anymoreTrey don't go to far out of his way for you too? Quote Success is only a stones throw away.................................................................for a Palestinian Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61292 Share on other sites More sharing options...
ThaddeusW Posted August 10, 2010 Share Posted August 10, 2010 Not really too physically large. They depend on airflow through the plenum to survive. Leaves and trash buildup on the cowl inlet screens take them out quickly due to reduced airflow. As Herv stated if the blower motor is run on the "high" position of the switch, the resistor is bypassed electrically and not in the circuit.RobYes I figured the resistor is used to divide the voltage for low speed. Why i said.. what i said, i have no idea, lol. For some reason I was thinking a few hundred watts but that is not the case.You can calculate the motors resistance using the formula R=E/I meaning Resistance (in ohms) equals the voltage (E) divided by the amperage(I). So for example: if we have a blower motor that draws 10 amps you divide 12 by 10 which equals 1.2. So to divide the voltage in half you need a 1.2 Ohm resistor. And since the current (amps) will also half, the wattage will be 6 volts times 5 amps which is 30 watts. So you don't need a very large resistor at all. I don't know why i didn't think that one out.You can easily source one from an online electronics supply company (digikey, mouser, newark) and just connect it. Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61327 Share on other sites More sharing options...
Rob Posted August 10, 2010 Share Posted August 10, 2010 Yes I figured the resistor is used to divide the voltage for low speed. Why i said.. what i said, i have no idea, lol. For some reason I was thinking a few hundred watts but that is not the case.You can calculate the motors resistance using the formula R=E/I meaning Resistance (in ohms) equals the voltage (E) divided by the amperage(I). So for example: if we have a blower motor that draws 10 amps you divide 12 by 10 which equals 1.2. So to divide the voltage in half you need a 1.2 Ohm resistor. And since the current (amps) will also half, the wattage will be 6 volts times 5 amps which is 30 watts. So you don't need a very large resistor at all. I don't know why i didn't think that one out.You can easily source one from an online electronics supply company (digikey, mouser, newark) and just connect it.Yes but a standard carbon based resistor does not release it's internal heat as readily as a ceramic case resistor does. I've seen standard plastic cased, carbon based resistors used in this application not hold up long at all.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61331 Share on other sites More sharing options...
rhasler Posted August 10, 2010 Share Posted August 10, 2010 i only have 1 mack dealer here. How would i go about getting it cause my dealer says that mack does not stock it anymoreI don't know if it can be drop shipped to you or not. I would tell your dealer that you know better and then give them the part number you need. Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61334 Share on other sites More sharing options...
ThaddeusW Posted August 10, 2010 Share Posted August 10, 2010 Yes but a standard carbon based resistor does not release it's internal heat as readily as a ceramic case resistor does. I've seen standard plastic cased, carbon based resistors used in this application not hold up long at all.RobYea, you would need a wire wound resistor. Either encased in ceramic or better yet, encased in an aluminum finned case to dissipate heat.You would need allot of carbon resistors to get 30 watts and 1.2 ohms Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61337 Share on other sites More sharing options...
buddy Posted August 10, 2010 Author Share Posted August 10, 2010 (edited) Yea, you would need a wire wound resistor. Either encased in ceramic or better yet, encased in an aluminum finned case to dissipate heat.You would need allot of carbon resistors to get 30 watts and 1.2 ohms Hey Hey, watch that fancy wordage, I am a owner operator and all my trucks are old enough to drink Edited August 10, 2010 by dunny Quote Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61357 Share on other sites More sharing options...
HK Trucking Posted August 10, 2010 Share Posted August 10, 2010 I am going to take a pic of it and go to freightliner cause i think you is rightThanks RichPS high speed does not work with this resister.If the blower does not work on the hi speed setting, then there's something else wrong.The resistor is not part of the circuit when the switch is in the high speed position, so therefore the problem could be in the switch, motor, wiring, circuit breaker, or it could be a bad ground. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61359 Share on other sites More sharing options...
buddy Posted August 10, 2010 Author Share Posted August 10, 2010 If the blower does not work on the hi speed setting, then there's something else wrong.The resistor is not part of the circuit when the switch is in the high speed position, so therefore the problem could be in the switch, motor, wiring, circuit breaker, or it could be a bad ground.there is some sort of diode on the hot side of the resistor. if i cross each end and the fan switch is on high then the fan blows your hat off Quote Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61372 Share on other sites More sharing options...
Rob Posted August 10, 2010 Share Posted August 10, 2010 there is some sort of diode on the hot side of the resistor. if i cross each end and the fan switch is on high then the fan blows your hat off That is an "anti spiking" diode. It basically absorbs and routes the transient voltage spike to ground when the switch is operated. Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/15192-resistor/#findComment-61374 Share on other sites More sharing options...
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