can anyone offer advice on how to change Part #127014 (#13) on the diagram ? is it possible to go through the center vents or is it possible to wire in an aftermarket transistor...or do you just have to take out the whole friggin' box ? thanks, Image Unavailable, Please Login
Be careful. The OP has a QV. You and I have a "T". I posted about the power transistor last March. The power transistor is in the center console for us. Inside the small plastic box that holds the speed control potentiometer is a small circuit board. The transistor is in that thing. I found it and alternates at Mouser and Digikey. There are other places that have it as well. I hope you are doing well. Here is my post from last March (never got time to fix this. I'm working way too hard): "I suggest you search Fchat for "Mondial fan control" or "TR power transistor" There are many discussions to be researched. My problem, and I believe it is a common problem, is the power transistor that controls the voltage to the fan on any speed other than full on or off. The temperature is controlled by a simple potentiometer but the fan speed control is actually a small circuit packaged inside a small plastic box. In the 3.2, 3.0 and possibly the 8 (all Mondials) the power transistor is mounted near/in the airflow of the center vent for cooling. In the "T" variant it is inside the plastic box in the center console and is somewhat difficult to replace without removing the potentiometer that is mounted directly above and is soldered to the circuit board. There are several alternate transistors the can replace the original, but one must be careful to not over spec the amperage capacity as the linearity of the circuit will be affected. All of these transistors are cheap (under $10). I will be trying several types to determine the best solution. The original, according to the info I found on Fchat is a 2N3055, 10 Amp. There are replacements @20 Amps (2N3772), 25 Amps (2N5886), 30 Amps (2N5301) and 50 Amps (2N5686). I think the main problem is heat. That poor transistor is cooking itself in a small sealed box with no chance of air flow to dissipate the heat. I will be experimenting with extending the circuit somewhere into the cabin (hidden of course) to help alleviate the main issue. I have just started this process so I can't give you an solid answer or solution...yet. I will be targeting the 20 Amp and 25 Amp transistor as replacements." DavidJ
Thanks for the heads-up David. I purchased the 2N5886G from Mouser. Its the replacement for the 2N5886 which is no longer available. I think the post from bretski clearly mentions that he has a "T". Did I miss something? Happy New Year, I hope all is well with you. Randy
You are correct. He does mention a T. There are currently 3 threads on blowers in the Mondi section. They are all next to each other and I just merged them in my mind. My bad. I might get to the mod I plan on making this spring. Good luck with the blower removal BTW. I will need to do it as well, soon. I have a blower fan bearing that is squeaking. Not a good sign. As one of the first to do this, I hope you take lots of pix. DavidJ
Same symptoms as mine. Bearing starts to rattle and it goes up in smoke when you least expect it. Do you have a BMW part number on the blower? If I remember correctly the blower is out of a 1988 BMW 5 series. I saw it in Fchat but I cannot find it now. There is always the possibility to have the bearings replaced in the original, but I like the idea of dropping in a new one! Cheers, Randy
David, Which did you end up using? I am getting no flow from by blower at any setting on the pot and suspect it is the transistor below the pot as you describe. How difficult is it to get to the transistor and is it a solder replacement? Any pics, etc. would be appreciated as I need heat flow here in Indiana now! Thanks much, Greg
Sorry, I was so busy with work I never got to replacing the transistor. Maybe this summer? My blower works at full speed or off. So with the Ferrari design of the ventilation system being what it is, full speed barely keeps up with the heat or cold. As a result I felt no pressure (pun intended) to make this a priority. My plan is to somehow remote mount the circuit board in a location where it can be kept cooler. Maybe I will install a small, slow speed boxer fan on a heat sink to make this issue go away forever. FYI the transistor is completely blocked by the potentiometer on the board. It will be a bit of a challenge to get it out. I might have to re-design the whole thing. Might be a bit of work. Like I said, not a priority right now for me. DavidJ
