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Subject: I have some pics and some tips Author: Shayne : member since July, 2005 : 6583 posts Posted on: 2007-05-11 23:57:35

3 symptoms I know of and there may be more:
1. Fan runs on high no matter what position including off: One or more MOSFETS have shorted.
2. Fan only works on high: one or more MOSFETS have failed.
3. Fan works okay but only if you place it in the high position then roll it back into the desired position every time you start the car. One MOSFET tests open.

Here is the Final stage unit before getting serious.


If you have the creamy epoxy shown in the first picture simply use a pair of side cutters and get under it and 'snip' it off. It comes off quite nice in one chunk. If you have the 'clear' epoxy you can snip it off (it isn't as brittle and needs a little more work) or use some heat to soften it and easily pop it all off with a screwdriver.


Back of the PC board with epoxy removed.


A simple solution to purchasing standoffs and other items. Drill out each rivet with a 5/64 bit. Then 'countersink' each rivet on both sides with a 3/16. This allows you to use a 2mm x 18 mm screw and the existing standoffs.


I drilled a hole in the wood to accept the temp sensor nut so the 'sword' would sit level.


I then drilled each rivet out with the 5/64 bit.


Then I used the 3/16 to remove enough rivet on each side so the PC board could be separated from the heat sink.
Desolder the 3 pins on each MOSFET.


Remove the nut on the temp sensor. Be certain to hold the inner side so you don't twist it.
Now gently pry it apart.




MOSFETs


I have a tool to bent the leads but any straight edge will do the trick


Bent to the proper shape


Install the ready to go standoff


And insert into the PC board


Solder them in place then use the 2mm x 18mm screws, washers, and nuts in place of rivets to assemble.


Install the temp sensor nut and the circuitboard cover and it's good as new!

Shayne
525iTA
533i
735iL



I don't know the same things that you don't know.

• So this is why my fan would always run- (pic) - stevebu 2007-05-09 18:54:04 (1311 views)
  • give it a try (url) - shogun 2007-05-09 21:22:05 (847 views)
    • I will -as always, thanks for the info! - stevebu 2007-05-10 06:34:03 (632 views)
      • here the expert answer - shogun 2007-05-10 08:45:35 (1094 views)
        • Excellent info, again. - stevebu 2007-05-10 19:29:38 (509 views)
          • make some nice pics of the repair. Thanks (nt) - shogun 2007-05-10 21:49:08 (614 views)
            • I have some pics and some tips (pic) - Shayne 2007-05-11 23:57:35 (20870 views)
              • Question: Pic 14 'And insert into the PC board': - stevebu 2007-05-12 08:20:59 (701 views)
                • Re: Question: Pic 14 'And insert into the PC board': - Shayne 2007-05-12 13:20:45 (608 views)
                  • Nice, I'll order up the mosfets. - stevebu 2007-05-12 14:43:27 (625 views)
              • And I should have mentioned (pic) - Shayne 2007-05-12 00:17:22 (1861 views)
                • Brilliant stuff Great Info Thanks. (nt) - slydon 2007-05-12 05:06:22 (572 views)