Pictures of Fan Transistor?

Any chance you could post pics of your project?
Are you referencing the sensor mounted in the air duct or literally a fan transistor?
Duct work is one of my next challenges.
Thanks,
Vince

 

The stock location for the TR fan power transistor is riveted inside the center AC air outlet duct (you have to remove the thumbwheel grate panel to look inside to see the power transistor and it's aluminum mount), but some of the professionals have mentioned that they sometimes relocate it into the bottom of the central tunnel just to make it easier to replace the next time. See this thread:

http://ferrarichat.com/forum/showthread.php?t=50589
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Thanks Steve - - that will likely be my job for next winter!
Rgds,
Vince

 

Yes, it can be moved anywhere, but its life will be even further reduced if not mounted in the outlet airstream (unless you do some more sophisticated heat sinking) -- maybe that's a reasonable trade-off (I put mine back in the stock location). Regardless of where it is located, the best thing you can do IMO to prolong life is not operate at speeds just under full speed (e.g., 3/4 ~7/8) -- which is just the exact opposite of what most humans do. We usually think "I'll turn it down a little from max", and this puts a very large current thru the transistor -- better to run full speed and put the large current thru the relay.

Yes, of course, if you have an early fan speed control ecu. My TR SPC is very foggy on the three versions of this gizmo, but, IIRC, '87 Owners have posted they had the fuse so there's probably one on your '86.

My own dash was a little molested when I first got it (hence the photos from my project to remove/reinstall/improve it), but I believe that you should be able to replace the AC fan power transistor without doing a big dash disassembly if you remove the air outlet grill and can manuever the small underpanel to get the rivets.

 

My fan only runs on high also, is there any way to test the existing resistor before removal? I believe think that if I do replace, I would try to use self tapping screws instead of the rivets. Then it would be easier to replace.

 

or perhaps a rivnut:
http://www.compcoinc.com/pdfs/RivnutDesignGuide.pdf

Rgds,
Vince

 

The referenced thread points towards a 'hinged panel' immediately below the central air vents.

So then, does it simply require a tug at the --top--- of the leather panel (immediately below the air vent) to get it to open for access?

Could it really be that simple?

Knowing FCar - I must be missing something.

Thanks in advance,
Vince

 

I'm unsure if all TR interior are designed exactly the same in this area, but on my late US TR that panel is designed to be hinged and spring-loaded so it could just be pulled down -- to give access to the metal clips on the bottom of the center air vent that need to be depressed upward to release the center air vent and to see/drill out the rivets. Although on my particular car this was an area that was molested and wasn't working correctly (so keep in mind that it may have been repaired improperly in the past like mine -- seems a delicate thing).

 

I tugged at my TR's panel a bit this evening - assuming a hinge located along the bottom edge. The audio feedback infers velcro, but the tactile feedback did not infer a hinge along the bottom edge. The tactile feedback may have been masked by a velcro type closure at the top of the panel.

I stopped before pushing my luck to check back with FChat. Is there by chance, velcro securing this panel? What mechanism holds it in the upright position.

As always, many thanks for your input,
Vince

 

Just replace the transistor yesterday. It is motorola stock # is 2n5886. My son who works for ON-Semiconductor got them for me. Actual cost 5Cents, real cost online $3.50 . Ferrari cost ? Labor, about 2 hours. The hard part was getting out the old rivets and re-soddering the new part into the old wiring harness. I reinstalled with metal screws, should be easy next time. In addition, my son gave me an aluminum heat sink that sets on top of the transistor. Maybe this will stop the melt downs. On my 87 tr the ac vent just pulls straight out, 2 metal clip/springs on bottom. Reach into the vent and on the lower right side there it is. You can not see it. drill out the rivets from under the dash, and you are home free.

Dennis

 

Any part number or description that we can look up online?
Thanks,
Vince

 

So you reach between the leather panels with a screwdriver?
Between the knee pad panel and the panel which abuts the vents?
Presumably then, the panel swings up and away about a hinge located at the top?

Thanks for your help - I REALLY hate the 'wish I didn't do that" syndrome.

Best regards,
Vince

 

Again, I'm not sure if this varies on different years, but the jpeg shows how it is on my '91:
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Miy vents came out very easy. There are no hinges involved. worst case slip a very thin putty knife just under the vents and work the vents forward gently with a screw driver. alternating from side to side.


You and buy the transistor on line here. Part # 2n5886
http://www.digikey.com/scripts/DkSearch/dksus.dll?KeywordSearch

 

EZORED - Thanks for the info. Did the transister you removed have a PN on it that you cross referenced? How did you determine that PN?

Discussion on the following thread indicates that these transistors can be doubled up in parallel to drop their loads & heat output - presumably in half. Their text is shown below for easy reference.
http://archive.ampage.org/threads/1/misc/019143/need_help_crossing_transistor-1.html

Any triple EEEs out there that can help interpret this stuff?

If these transisters cannot be mounted in parallel - any suggestions for a heat sink PN?

It sure would be nice if any easy upgrade fixed this recurring problem once and for all.

Rgds,
Vince
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OT's (output transistors, that is ) blow because either (a) they get too hot or (b) they exceed their safe operating area and a small part of the chip shorts internally. You can use "bigger" transistors, more rugged transistors, put in protection circuits, etc, but the best and usually cheapest thing to do is to put in more OT's in parallel. On the same heat sink, put double the number of transistors, using a new 0.25 ohm resistor in the emitter of each transistor, paralleling the bases and collectors.

This is usually cheap, at most about $3 a transistor, down to about $0.60 a transistor for 2N3055's, and has the effect of doubling both the current capability and power dissipation capability of the output stage, while *halving* the equivalent temperature rise from the heat sink temperature on *both* transistors, and *halving* the exposure to safe operating area failures.

Why don't manufacturers do this? Well, while an extra $6-$8 for another OT pair is small compared to us paying a repair bill, it is a HUGE increase in parts cost to them. The economy of scale is working against them. We can do it once, cheaply.
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The existing transistor had that part # on it. It was obvious that it had been replaced in the past by the previous owner. As stated, I did add an additional heat sink that fitted over the top of the transistor, but It was given to me by my son who works for On Semi, and had no part number. He actually gave me 3 styles to try so they must be readily available some where.
Dennis

 

That would be usually be "1A" (a current rating) not "1V" (but there's usually a maximum usuable voltage given too so not uncommon to have some sort of "V" marking also), but I can't really comment on the impact of slow vs fast blow because I don't have information on the circuit nor where/how the fuse is used. Somehow they eliminated it completely in the later TR units like mine, and I don't know if they did something clever that really allowed it to be eliminated safely or if they eliminated it just because false failures were causing more problems than the protection it rarely (truly) provided .

One comment I'd add is that if your fuse has been replaced before don't assume they replaced it with the stock item (I don't know if a 1A fast blow fuse is not stock or if it is stock -- have you checked the WSM?).