Hi All,
This is a new (I think, after searching the forums) twist. Here is the story so far:
I have a 1986, Australian delivered 635 with A/C etc. It is in really good shape/unmolested. Some weeks ago the car started blowing fuse 20. I changed the A/C blower transistor (I think it was actually a short around this transistor, not the unit itself). All worked well at this point.
Last week, I had that terrible electrical smoke smell, and then blowers only worked on high. As per the great info on this site, I removed the dash blower fan controller, and just as the voices of experience had predicted, was a seriously fried original transistor.
I replaced the transistor with the beefier TIP3055, and here is where things went odd. reconnecting everything in the dash to test, the blower fans (one at a at time depending on A/C switch position) run on (very nearly) full blast, regardless of fan knob position. when I go full speed setting (micro-switch click), there is a slight increase in fan speed (again either heater or A/C depending on A/C switch position).
After pulling the controller apart (several times!) checking the transistor and its junction continuity etc, checking the variable resistor function etc, I put it all together and tested again. same issue.
Here is what seems odd to me. I then pulled the main (four connector) plug out of the speed controller. exactly the same behavior (ie fan on 90% , micro switch makes it 100%).
I pull the A/C switch out. exactly the same symptoms.
I have the ETM and can only guess that some 90% voltage is leaking in, but cannot understand where that might be.
I have had to pull fuse 20 to turn the fan off!
Any advice on troubleshooting this would be very gratefully accepted.
Toby
Blower fans run all the time - without switch
Moderators: GRNSHRK, ron, bfons
Blower fans run all the time - without switch
1986 635 CSi Lapis Blau with Anthrazit buffalo
1988 911 3.2 231HP Grand Prix white (Sold - 13 years of Zuffenhausen fun))
1984 BMW R80 G/S Dunkel Blau
1982 Yamaha SR500 scrambler
1988 911 3.2 231HP Grand Prix white (Sold - 13 years of Zuffenhausen fun))
1984 BMW R80 G/S Dunkel Blau
1982 Yamaha SR500 scrambler
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Re: Blower fans run all the time - without switch
Try changing the transistor, or even try fitting another circuit board?
Re: Blower fans run all the time - without switch
Thanks POD,
It's interesting that the car operates identically with or with out the controller plugged in. Or am I missing something?
I would love to try another circuit board, but they are not that common here in Oz.
I will keep looking.....
Cheers,
Toby
It's interesting that the car operates identically with or with out the controller plugged in. Or am I missing something?
I would love to try another circuit board, but they are not that common here in Oz.
I will keep looking.....
Cheers,
Toby
1986 635 CSi Lapis Blau with Anthrazit buffalo
1988 911 3.2 231HP Grand Prix white (Sold - 13 years of Zuffenhausen fun))
1984 BMW R80 G/S Dunkel Blau
1982 Yamaha SR500 scrambler
1988 911 3.2 231HP Grand Prix white (Sold - 13 years of Zuffenhausen fun))
1984 BMW R80 G/S Dunkel Blau
1982 Yamaha SR500 scrambler