Good day since last Summer, and only of a sudden, the fan blower speed control in the center consolle of my 1987TR just work on an on and off basis. It is impossible to regulate the fan speed. Nothing happens until the speed knob is virtually 1 mm from the end of its stroke. At this point the blower work basically at full speed. Now the garage tell me is the fan motor which need to be changed. Since this is a dash out job, and before entering into this new adventure, is there any way to check if the problem could not be in the potentiometer speed regulator ?? Any idea ?? Tks for any help on this matter Gianni
Do a search on "TR power transistor", and read those ~20 threads. If you blower motor runs well in the full speed mode, it does not need to be replaced IMO (and the trouble more likely is the variable speed electrical system -- the power transitor, the fuse on the speed control switch/ECU, or the speed control switch/ECU itself).
Loose screw on my power transistor board fixed mine with exact same symptom. 100% agreed with Steve that if the motor spins fine a full speed then its not the problem.
If fan works on high it is definately not your fan motor! It will be the transistor sits in a heat sink that is riveted inside the air outlet duct below your radio. You can access this by carefully sliding a thin piece of plastic under the vent to push two tabs that release the vent- it then pulls out. Take off the trim panel to allow access for small drill or dremel to drill out rivets that hold the unit in the vent. Remove/unplug the unit and it is simply a matter of some minor soldering skills to replace the transistor. I found 2N5886G or equivalent will work well. There is a thought that it may be better to mount the unit on the outside of the unit to allow air circulation, however to keep it original I mounted it back inside, also I usually run my A/C on cool so that should assist with keeping the Transistor cool- they do get Really Hot! Good luck
Greetings.. any idea as to where to purchase this transistor.. I have been wanting to do mine for a long time now.. I like having fan speed adjustments eventhough it will probably blow out again.. Thanks R
Robbie, you should be able to order on line from any good electronics supplier. I think the original no was BDY29 GE/RCA V 8901. If you simply search BDY29 it will come up with Data sheets etc but I found it was not available so got an equvalent product.
I replace mine with 2n5886 E made by On semiconductor also says Mexico Bm0349 The hard part is finding a company that will sell you only one. Also ask for a heat sink for it that fits over the top. I put one on mine and I have had no trouble for 2 yrs here in AZ. Dennis Try this link http://us.element-14.com/jsp/search/productdetail.jsp?SKU=01H1385&CMP=KNC-G10000895
Hi have been finally got to change the power transistor, and whilst in there have added a cooling fin, however, the on/off blower status has not improved at all. Obviously the old transistor was, in fact, good. Now the question, could it be the potentiometer on the tunnel ? Any other idea where to look whilst the car is apart ? Tks Best Gianni
I am frantically searching for a thread about this from a few years ago that I posted a pix of the transitor packaging w/info.........but can't come up with it.........but in the interim..............there is also a FUSE I believe in the potentiometer if I remember correctly!! Check that also.............and please if I am blowing smoke, someone please correct me!! FOUND IT!!!!! http://www.ferrarichat.com/forum/showthread.php?t=102194&highlight=TR+power+transistor Oh yeah, Just to put some sunshine on this subject....I have yet to get mine to work properly!! Looking elsewhere Me Image Unavailable, Please Login Image Unavailable, Please Login
Tks yours Kerry. Well, at least yours worked properly for a short whille with a new fuse. Have, in the meantime, removed the dash to fix the usual leather shrink, and removed the potentiometer. My fuse is good, so it cannot be the cause. Noticed that the potentiometer used is welded into a small board circuit with few components. Wonder is something went bad there. Btw, the potentiometer in my car, has a switch once fully turned counterclockwise. Is this normal or is it a sign it has been already replaced in the past ? Any advice how to test if the potentiometer is doing its job properly ? There are six wires coming out the black box... Best Gianni
My name is George "Kerry" Washington and I can not tell a lie................Gianni I haven't a clue!! Take in to account that mine is still NOT working properly....LOL!! Mr Steve Magnusson may have some insight...he is the TR electric Guru here on FChat. Chopping down the cherry tree Me
Unfortunately, there are two different TR AC units and three different TR speed controls (and the wiring is a little different) -- and your report of having 6 wires on the fan speed control unit makes me think that you have the early type (maybe with the built-in 1A fuse). What they all do have in common is that all three are based on the "common emitter" principle for the variable speed operation -- i.e., the emitter is always connected to ground; the fan speed control electronics puts a small current into the base (that flows to the emitter-to-ground), and the size of this small base-to-emitter current determines how much current flows in the collector-to-emitter path (and the minus side of the fan blower motor is connected to the collector so this controls how much current flows thru the fan blower motor and sets its speed). What I would do is: 1. With the AC system "on" and the fan speed control set to ~1/2 speed (so the fan blower motor should not be running at all per your report), use a jumper wire and connect the collector (the metal case of the transistor) to the emitter terminal -- if the fan blower motor runs full speed, this is good, and shows that the emitter is properly connected to ground; if the fan blower motor does not run full speed then you have some sort of problem in the wiring that should (always) have the emitter connected to ground. 2. If #1 is OK, connect an ammeter into the wire going to the base terminal. With the AC "on", the current in this wire should change as you move the fan speed knob from off to ~7/8 maximum. If you have no current in this wire, that is a bad sign for the speed control unit -- but also make sure that you have checked that the small (1A) fuse (if so equipped) on the fan speed control unit is OK. Otherwise, if you do some searches on terms like "base emitter" or "power transistor", and you should get some prior threads like this: http://www.ferrarichat.com/forum/showthread.php?t=209296 Good hunting!
Tks Kerry and Steve. @Steve indeed my TR is an 87 model so quite an early one. And, yes, the fuse is 1 A and is mounted on the small box containing the speed control. Will try as you suggested, however, it will take some time since, as said, the entire dash and central console are out of the car at present. Just for my piece of mind, is it normal that sped control knob has a switch integrated ? Best Gianni
Unfortunately, my TR is at the Shop at the moment, and it's got the later style fan speed control knob (no 1A fuse) so not sure that it would be a good comparison anyway -- so I've got no information one way or the other.
Hola' just a short update. It seems the problem is the potentiometer, or better say, one half of it. The poti is a double one with switch. Having removed it from the small circuit board and measure it, it seems that one half is doing a proper job whilst the other half is not. Now the bad news, whilst it seems difficult enough to get a double one with switch,there is no indication of the impedence on the Poti nor if it is linear or logaritmic type... Any idea ? Tks Gianni
Hi since was asked by user Melvok abt fixing of the potentiometer, have revisited this post. First of all had to removed the control panel on the center console, well, actually have removed the entire dash and the console 'whilst i was in there' as Shamile would say Then i removed the entire fan control unit. There are different control units for the TR and, unfortunately i was not able to get a used unit to match my car. Decided, then, to dismantel the entire unit. After having open the black box, have unsoldered the potentiometer from the small circuit board and could measure the impedence on each half and spotted that the lower half had no impedence at all. I did separate the lower half from the upper by straightening the bended metal tab on the cover. I could then gain access to the heart of the potentiometer, the trimmer. The total measured impedence between the left and the right pins of the working half gave me 100 Kohm. I could find a double potentiometer of 100 Kohm at the local electronic shop for few dollar. Since this one had a different shape than the original and no switch, took it also apart to gain access to the trimmer itself. The second pic below shows the trimmer removed from the original unit with no impedence at all and the third pic the trimmer removed from the new unit. Pic number four shows the old and new trimmer togheter (right new, left old). The shape is not 100 oct the same but, with a bit of work, the new trimmer can be fit in the old body. Re-installed it on the board and the entire control unit back on the panel. Whilst in there, and altought it was not the cause of the fan not working, have replaced the power transistor and, as a precautional measure, added a cooling fin to it (pic 5). After having redone the front dash cover (usual leather issue), have reinstalled the all dash and center console and the fun control unit works just fine. Have not tested the car on the road since we have temp as low as minus 22 C at the moment, but am sure it will work fine when summer comes again. Best Gianni Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Gianni, perfect description so ... many more may try and repair these buggers themselves when it occurs.... Can you please post info on the donor (new) part ... how is it called, have a picture in original state ? Any pics on this: "I did separate the lower half from the upper by straightening the bended metal tab on the cover. I could then gain access to the heart of the potentiometer, the trimmer. " Did you check the aircon motor for possible bad bearings (like I had in the 512TR ...) ? And O.T. what seats do you have in th car ... ? Thanx !
Sorry Mel no pics available. Anyhow is very simple and easy to figure out. The original potentiometer is double with a switch to turn the system on and off on the lower end. Each half is actully a stand alone unit. The rotation shaft on the upper half, continue till the bottom of the case with a pin into which the the shaft of the lower half will insert. The housing of the lower half have 4 small metal tab which will enter into the upper case. By bending these tabs the two half will become an unit. The new one is simply a double linear potentiometer of 100 Kohm impedence. Visually they look very similar, althought the new one had no switch and was a little bit shorter. That is way i decided to maintain the original housing and just change the 'heart' , i.e. the trimmer you see in the pics. OT : They are OMP racing seat with 4 point harness. Have them in the car since 8 years. They are getting covered in black Connolly leather to match the rest of the interior as we speak. best Gianni Image Unavailable, Please Login Image Unavailable, Please Login
