This seems to confirm that it is indeed an ASIC part:
Translation: Received a response from tehpodderzhi Elmos, cultural refused. ENGLISH: Thank you very much for your interest in our products. Unfortunately we are strictly not allowed to provide any information concer ning the E109.01D to you as this product is customer specific. Best regards, Sina Staufenberg staatl. geprüfte Betriebswirtin (Recht)
Hi.I managed to fit the fsu right behind the glove compartiment.Added a little fan ,but the hvac doesn't have a +12 so i made a circuit with an 10k ntc that allows the fan to start only when it gets hot The copper strip is just a bypass for the +12 of the blower . The radiator that i used is all copper and a had to isolate it because when it touches the ground(-) the blower comes on at full speed. I made the test on low speed half hour and it stays warm.
The fsu gets really hot at low speeds so the air flow its not enough to cool it down.At hi speed its cold .So that why i decide to add the fan .A cpu cooler will do just fine. I did drill a hole were the transistor has that hole to be placed on a heatsink and added a screw so that the heat transfer is better in that area.
Saw your pics and sounds like you have a good design there that should work. The idea of just making the fan go on when it gets hot was a good one, so you could then just tie it to the 12V that is already there. If you tied the fan to the 12V for the blower, you might want to put an inline fuse in. That blower circuit is
30A? I've never seen a CPU fan like that cause a problem, but just a thought. The fan may have some kind of protection of it's own though, so manybe it's not an issue.Good idea to screw the transistor down. I noticed that in the photo, it wasn't clear exactly how they had it secured down. And it's also near one edge of the heatsink, instead of being in the middle. Before you modified it, was there thermal paste between the back of the board and the heatsink?
This is just a really bad design. If they had correctly bonded the heatsink directly to that transistor where all the heat is being generated, I bet it would work fine.
The original fsu board was tied down only on the edges by that black plasti c which was clipped by some small fins of the aluminium radiator .It did ha ve a thermal paste i also used a paste . The +12 i took from a main +12 and used a 2.5 amps fuse . The transistor i think disipates about 50w to 80w of heat at low speeds tha t makes the heatsink to small to dissipate that heat and the airflow of the blower at that speed is too little.Its true the transistor is made for 250 degrees but lets be true they dont make like they used.
tic which was clipped by some small fins of the aluminium radiator .It did have a thermal paste i also used a paste .
hat makes the heatsink to small to dissipate that heat and the airflow of t he blower at that speed is too little.Its true the transistor is made for 2
50 degrees but lets be true they dont make like they used.I think it's probably generating more heat than that. The transistor is rated at 300W. In any case, I don't think it's the power transistor's power handling capability that is the problem. It's that the heat causes other parts to fail. I'm sure you've seen pics of ones where the solder joints came undone. IDK what causes the one here to basically shutdown once it gets too hot, but suspect it's something to do with the Elmos chip, either by intentional design or that it just shuts dowm by malfunctioning from the heat. Whatever the max operating temp is for that Elmos ASIC, I'll bet it's being exceeded when these things fail.
The overall design is probably just enough if everthing works like it should. If the blower winds up pulling some more current than normal, for whatever reason, then it pushes it over the edge. I'm thinking as Ralph suggested, it's probably the blower that's the root cause here. And to fix that requires pulling the dashboard in the X5. Another great design. Not something I wanted to do 30 years ago, but today with all the air bags and God knows what else crammed in there, it's got to be a lot worse. Wish I could get some oil to those motor bearings and see what happens.
Going back to what Ralph said about bearings, I'm not convinced that the blower is putting out full RPM even when it's connected to 12V directly. There ia a lot of air coming out, but I think it may have been even more previously, hard to tell for sure. But if it is putting out less at full, then that could be a sign of the bad motor bearing thing. Another sign I think is that it seems even when you first start it up, with a cold FSU, it seems to me that the airflow at say mid speed is more like airflow at 1/3 speed, etc.
Good luck with your project at let us know how it works after you've had it running for awhile.
The heatsink of the unit needs to be where air can circulate past it. The fan is a good idea. I am not sure how the transistor is fastened to the heat sink. It needs to make good mechanical contact with it.
When you use the thermal paste just use the smallest ammount you can. The paste is not really that conductive of heat. It is just beter than air. You want the transistor to make good mechanical contact with the metal of the heat sink. There are very small inperfections in the metal that has air voids in it. The object is to just fill the air voids. Too much paste is worse than none at all.
I know that it needs a space with more air thats why im thinking of rellocating the fsu in the engine compartiment,but im waiting to get warmer outside. The transistor is now fastened very good not like the original were it made contact only on the margins of the copper plate
The power transistor is not fastend to the heat sink at all. If you look at the pics, it's on the top side of the PC board. The bottom of the PC board has copper over all of it. Then the bottom of the PC board contacts the heatsink. So, you have the PC board material in between, which is not a good heat conductor. And the transistor is closer to one side of the heat sink and no bolt through the usual bolt location provided.
And to top it off, these things have been failing for 10+ years and not one of the many suppliers has seen fit to make some of the simple changes that would fix it.
Its directly on the copper plate.The pcb has a rectangular hole .its tinned
Unlike the older models when the transistor heated up it transmitted the heat to its pins ,now the heat transmits to the whole pcb thanks to genius who decided to glue the pcb to the copper
I just discovered something important that I haven't seen mentioned here or in any other threads on the BMW blower motor resistor (aka final stage unit) problems. This module is mounted in a location where the heat sink fins are directly in the blower motor airstream. It relies on the blower air to keep it cool. From where it's located and how you remove/install it, it's not obvious that the heat sink fins wind up in the blower air, because you can't see where they actually are.
When I replaced it, to make sure it worked before putting it together, I just left it hanging for testing. It overheats as soon as you slow the blower to about 80% of full speed and stops working. Once I stumbled on the fact that if it's mounted it gets air flow to cool it and I mounted it, it's apparently working. Just thought I'd pass that along, as it seems like something that could trip up a lot of people.
Hi, I am frustratingly having similar issues with a FSU on a 2002 E39 and on the topic of why does the FSU not fry up any quicker when the blower motor is suspect, mine did just that. It lasted all of 2 months!
I'm an atty investigating this problem & car fires. Plz call my cell: 1-800-279-6996 or email me your cell: snipped-for-privacy@aol.com if you suspect your BMW fire was due to blower fan resistor (Final Stage Unit) failure. Thx. Jos. Santoli, Esq.
Pretty sleazy when lawyers resort to trolling here for new fish.
Hello, this might be a little late for this particular post but, I just finished fixing the blower motor on my '98
740iL. Basically all the motor needed was a new set of carbon brushes I got off eBay. In order to test the motor and FSU ("resistor") assy, just apply the following signals: 1 2 3 4 5pin 1: Ground pin 3: +12V (preferably from a battery providing high current) pin 5: 0 - 7volts (DC) to control the fan speed: 0volts = fan off 7+ volts = fan full speed
Good luck!
Did you enjoy taking the dashboard, center console, steering wheel, air bags and all the other crap out to get to those brushes?
I'm going to test a theory, that few if any FSU units are "fried" what is h appening is corrosion on the plugs and pins cause erratic behavior dependin g on which are corroded. One pin will cause it to run when the vehicle is o ff and another might let it run only on high. Being analog systems this typ e of problem was common to "that" I have 3 units and I will interchange aft er cleaning. The pins appear to be a poor quality metal that is reacting to the copper female plug
happening is corrosion on the plugs and pins cause erratic behavior depend ing on which are corroded. One pin will cause it to run when the vehicle is off and another might let it run only on high. Being analog systems this t ype of problem was common to "that" I have 3 units and I will interchange a fter cleaning. The pins appear to be a poor quality metal that is reacting to the >copper female plug.
I don't doubt that some problems are due to that. I've seen it once myself . However I doubt most of them are due to it. The draining current when the system is off mode for example. It's basically power transistors in a module and unless they have some very bizarre design, there is no way removing or degrading a connection can turn it on. Are you sure those female connector pins are copper? That would be very unusual. For the times I thought it was a connection issue, I slightly bent the pins in various directions, then connected it, figuring the increased pressure would help. I think that might have worked one time, but it could also be that cracks develop inside the circuit on the module and fiddling with it restores it temporarily. If you think you have a connection problem, there is electrical contact cleaner. That followed by dielectric grease which would prevent it from recurring could be worth a try.
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