Great outcome. Thanks for sharing, Miroljub,
A fantastic, most professional job Miro. Look forward to getting back in the car. Thanks again for taking on the project and share your skills with the rest of us on FC. Let me know via PM what I owe you. Given how much these things are worth (should you ever find one) I would highly recommend to all others that rather than trying to fix it yourself and run the risk of trashing it completely...!?. Send it to Miro and get it professionally done. Assuming of course Miro you would like to make some pocket money out of it. Up to you
Sorry for the delay in getting back to you Miro but finally got the fan speed controller back in the car. Went for a nice long drive (with the A/C on as it was a nice sunny day today) and the fan speed controller worked perfectly through the entire speed settings range... Nice to have my HAVAC 100% functional again. Thanks again for everything. Hope you manage to get some work out of this for yourself. Best Regs from Oz
Resurrecting an ollllld thread, as I'm chasing this now. @m.stojanovic what's this between the transistors? another diode? Image Unavailable, Please Login I'm chasing the fan speed issues right now. I have signal correctly variable from the dash, so the trouble seems to be in the board/chip/SMdiodes. My layout differs a little from what's pictured, but is essentially the same. sjd
The "thing" between the transistors is a thermistor (NTC resistor) for thermal protection of the transistors. I don't think there is any problem with it (they very rarely fail) but you can test it with an ohmmeter. I cannot remember the reading but it is probably around 100 Ohm at 25C, higher Ohms when cooler and lower when warmer. What usually fails is the power transistors although I have seen one case of cracked PC board. You can bench test the module as per diagram I posted in #31 here. I am currently developing a prototype replacement fan speed module using a similar shape but much more powerful unit which uses a pair of MOSFET transistors. This pair of MOSFETs can handle 150 Amp and is rated at 570 W, as compared with the original Ferrari pair of standard transistors that can handle only 20 Amp, rated at 250 W. I will inform when the first module is successfully bench tested (I am currently building a small electronic circuit that will adapt the module for use in 348/355). Image Unavailable, Please Login
I was getting in the mid 90's. I bench tested the module and I've changed the power transistors, and they still don't test correctly. I'm only a Mechanical Engineer, so I'm learning as I go. Something else is failed/wrong. maybe a cold/broken solder joint somewhere? the chip? I'm starting to think the signal isn't getting to the power transistors... I'll be looking forward to seeing the new part! All the best, and happy new year! sjd
Possible something else. The crack (hairline) I mentioned was on the small PC board, where the chip sits, so the signal was not getting through to the power transistors. Inspect your small PC board with a strong magnifying glass. Happy New Year
It appears that sometimes the small PC board cracks due to heat generated by the power transistors. I tried to bridge the broken traces ("micro neurosurgery") over the crack on the board I attempted to repair but no success. After bridging the traces on one and the other side of the board, I found out that there is actually a third layer of traces sandwiched in the middle of the board (a 3 layer PC board).
Seems to be FIXED!!!! My tech at work was having a slow day so she went over every solder joint, and when she got to one of the capacitors, it was loose, and the foil came off the outside. She pulled it, and replaced it, and I just went and tried it out, and all the speeds work! Miro, I have a different board rev than previously pictured. Image Unavailable, Please Login Image Unavailable, Please Login
Yes, there at least two different looking PC boards. It appears that the components are differently arranged but the microchip is the same (LM2901D). The second pic shows the one with a crack around the middle (the one I tried to repair). Image Unavailable, Please Login Image Unavailable, Please Login
I am now about to finish the first "prototype" - adaptation of a blower speed controller which will be good for the 348 & 355. The adaptation (addition of electronic circuitry inserted inside the controller) is based on an original (used) similar controller from another European car, not a China made knock-off. As this controller has the mounting "ears" placed higher (see pic), I have made spacers so that it can be bolted onto the 348/355 heater/evaporator box. Due to the added spacers, I will need to get longer screws. If anyone has the original mounting screws, or currently has easy access to them, please let me know the screw diameter (over the threads) to save me the trouble of ripping out the lining in the trunk of my 348. The controller I am modifying: Image Unavailable, Please Login
I measure 4.5mm on the outside of the thread (major diameter), and 17mm long (under the screw head to the tip). Will these plug in to the factory wiring? I'm in need, as my controller has gone out again. sjd
What are the symptoms when it fails. I have a spare but it seems the oem design was an issue, I am in favor of a better one.
I have zero fan up to 100% fan, then I have 100% fan. Once on 100% fan, it seems to stick there, but only sometimes. It's same thing it did before. A tech I had found a blown capacitor, worked for a couple months...now back to its old shenanigans. I don't have access to that tech anymore. sjd
Thanks for the info on the screws. The fan controller I am adapting is much more powerful/robust (150 Amp, 570 W) than the original one (20 Amp, 250 W). The unit also uses MOSFET transistors which dissipate much less heat as the fan control is PWM (Pulse Width Modulation). The original controller is "analogue" where the function of its power transistors is something like what resistors do so they generate a lot of heat. The controller I am adapting has very different connector sockets: Image Unavailable, Please Login so I intend to provide separate "pig tail" wires with suitable male spade/pin terminals attached that would have to be individually pushed into the Ferrari loom connectors. Will post pictures of the completed controller a bit later.
I have completed the prototype and subjected it to rigorous testing (on the bench) using a cooling fan of similar power as the Ferrari blower fan. The two power transistors of this module are rated at 570 W (total of the two), more than double the power of the original Ferrari controller and otherwise about 5 times the blower fan power which is probably about 100 W. Without any air flowing through the module's cooling fins, they were getting warm but never so hot that I could not hold my fingers on them. The main part of the modification was adding an electronic circuit inside with a microchip to act as an "interpreter" as this module is speaking French and the Ferrari AC ECU is, of course, speaking Italian. Image Unavailable, Please Login Image Unavailable, Please Login As it was impossible to find female connectors to match the Ferrari loom male connectors, I added pigtails with suitable terminals to be individually plugged into the two loom connectors. To make the connection easy, I have added templates that "imitate" the shapes of the sockets of the original Ferrari module - easy to know which pin goes where. I also tested the module on my 348 but, as I have completely modified my (failed) AC ECU, I was unable to test the function of the wire that is plugged into the middle socket of the small connector. The yellow wire is the main one for the blower speed control (outer end pin of the connector) and the grey wire, the middle pin in the connector, just provides feedback to the AC ECU of the controller temperature (via a thermistor), probably so that the AC ECU can shut the controller down if it gets too hot. However, this "protection" does not seem to work on the original Ferrari controller as there were many cases of its blown power transistors. The signal of the grey wire of the new controller is exactly the same as that coming from the original controller. This signal is not essential for the blower speed control but its absence may cause a fault code from the AC ECU. The third, inner end, pin of the small connector has no function as it is not connected to anything inside the original controller thus the new controller has no pigtail for it. Steve (steved033), Since you are the first member who has shown direct interest (and you seem to need a working controller), I have the following proposal to you: I can send you the prototype controller for testing (keeping if you are happy with it) and you first just pay the shipping cost. Unfortunately, Malaysian Post has, due to Covid, completely stopped international parcel deliveries so I can currently ship only by DHL at USD 70. Then, if the controller works well (no fault codes etc.), you send me another USD 130 and keep the controller. Alternatively, you can just send me the original (bad) controller which I may be able to fix (my risk). If the new controller does not work well, you send it back to me and I pay the shipping cost. What do you think?.
I am interested in purchasing your new fan controller. I have been chasing the same problem. Great work ! Thanks, J Glen Wesanko
I have sent the "prototype" to Steve so let's first see the performance results (will be shown later in this thread). Once confirmed that it is working well, I can offer it to anyone else interested. I currently have a few more donor modules and components for their conversion.
Miro's part works great! I did the initial plug in, there were no codes, and my fan cycles through all the speeds easily. His wiring loom holders/guides make attachment to the factory wiring easy, even if one of my plugs is a little loose and a pin keeps slipping out. I've got some CAD started to 3-d print a wire clamp solution that allows the factory plugs to plug in. sjd
You can try extracting the loose pin (socket) from the loom connector and see if you can "squeeze" it a little bit. There is usually a small rectangular opening in the connector body right next to the pin/socket in which you need to insert a suitable very thin rod to push on the locking tab of the pin inside and pull it out from the back. Otherwise, the gold plated pins I have attached to the controller's pigtails have the same diameter as the original pins, perhaps a tiny bit (0.05 - 0.1 mm) larger than the original pins which I thought was good for just slightly tighter sitting in the loom connector's sockets.
