Anyone actually have the blower power transistor be the cause of blower running on high only? I see where the service bulletin for this suggests 91's and 92's up to 000697 can have a problem with this transistor causing the blower on high only--just like the circuit board. I had the circuit board go bad 5 months ago and sent it to Langguth for repair. The system worked fine until yesterday. A local friend with a spare board let me try it today, and still only runs on high--so now I think it may be the power transistor--but my car is just outside the range for the service bulletin and the part is >$200--I'd hate to buy one and have it not be the problem. Just wondered if anyone ever had the transistor be the cause, and if anyone ever bought one and did not need it??
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Blower Power Transistor
- Thread starter Joe Gliksman
- Start date
Blower still only blows on high........
OK--now this is really frustrating. Following the manual on testing the heater/blower power transistor, it says to check the voltage with the switch at low and medium settings--I get 6.8 volts at all settings? Does this mean the power transistor is bad? It reads zero when the fan switch is either on all-the-way high, or all-the-way low with the temp set at 60, which I think is correct--all other settings I get 6.8 volts which seems incorrect--the manual does not say? As I posted earlier, when I tried a friend's spare board, the blower still only blows on high. I hate to buy a $200 power transistor if that is not the problem, but it seems like it is either that, or the board. Anyone ever have the power transistor be the problem? Anyone in the Tampa Bay FL area have a spare power transistor I can use for 5 minutes?
OK--now this is really frustrating. Following the manual on testing the heater/blower power transistor, it says to check the voltage with the switch at low and medium settings--I get 6.8 volts at all settings? Does this mean the power transistor is bad? It reads zero when the fan switch is either on all-the-way high, or all-the-way low with the temp set at 60, which I think is correct--all other settings I get 6.8 volts which seems incorrect--the manual does not say? As I posted earlier, when I tried a friend's spare board, the blower still only blows on high. I hate to buy a $200 power transistor if that is not the problem, but it seems like it is either that, or the board. Anyone ever have the power transistor be the problem? Anyone in the Tampa Bay FL area have a spare power transistor I can use for 5 minutes?
Hi Joe - is the price for the transistor assembly, with heat sink and mounting hardware? Seems like one of our electronic gurus here could recommend a transistor part # that an electronics distributor could get. No way any power transistor should cost that much. Then just get out the soldering iron and go to work, and mount it to the old assembly. Just an idea.
Hey Tom,
Actually, I did get a message from one owner who did just that. He carefully dug the transistor out of the epoxy and replaced it--said both Honda and Cadillac use the same transistor and it cost him 4 bucks. Still, hate to mess with it before I'm sure it is the cause. I can pull the transistor out, and it acts just the same--blower only runs on high with the transistor out! Someone out there must have replaced this and had it been the cause--and I'll bet someone out there bought one of these and it was not the cause and has it sitting around.........?
Actually, I did get a message from one owner who did just that. He carefully dug the transistor out of the epoxy and replaced it--said both Honda and Cadillac use the same transistor and it cost him 4 bucks. Still, hate to mess with it before I'm sure it is the cause. I can pull the transistor out, and it acts just the same--blower only runs on high with the transistor out! Someone out there must have replaced this and had it been the cause--and I'll bet someone out there bought one of these and it was not the cause and has it sitting around.........?
Transistors usually fail by forming an open circuit - the same as pulling the transistor out of the circuit. So pulling the transistor should act the same as a broken power transistor. Having the wrong control signal to the transistor can also cause the failure - bad control board.
I'd also be careful about digging a transistor out of epoxy and trting to replace it. The epoxy is there to carry off the heat. If you don't backfill the epoxy correctly, the transistor will heat up more than it should and fail early. Power transistors usually fail from excessive heat. This is why car companies replace the entire assembly. Getting the right thermal connection to the heat sink is not easy.
I'd also be careful about digging a transistor out of epoxy and trting to replace it. The epoxy is there to carry off the heat. If you don't backfill the epoxy correctly, the transistor will heat up more than it should and fail early. Power transistors usually fail from excessive heat. This is why car companies replace the entire assembly. Getting the right thermal connection to the heat sink is not easy.
Yes, replacing the power transistor will probably fix your problem, but it may return. My 91 is also after the serial number that are supposed to be effected by this problem, but when I replaced the transistor, it fixed the problem only to return one year later (luckily within the warranty on the part). If you read the service bulletin, if I remember correctly the blower motor is drawing too which current and causes the power transistor to blow. After the second failure, I also had the blower motor replaced and the problem has not resurfaced.
Bob
Bob
Joe
Just to get this correct, your blower only runs when the fan control is set to its highest setting?
When you turn the fan to its highest setting the transistor is bypassed by a relay. Normally when the fan runs only on its highest setting the problem is with the ccu board but since you tried a different board it must not be the problem. Look in the NSX parts for sale section or do a search for blower modules. They come up for sale once in a while from cars that have been stripped for track use.
The transistor is a Toshiba 2SD1460, it is screwed to the heat sink but the connections are all potted in epoxy so it would take a little work with a dremel tool to get to the connections but not impossible.
Just to get this correct, your blower only runs when the fan control is set to its highest setting?
When you turn the fan to its highest setting the transistor is bypassed by a relay. Normally when the fan runs only on its highest setting the problem is with the ccu board but since you tried a different board it must not be the problem. Look in the NSX parts for sale section or do a search for blower modules. They come up for sale once in a while from cars that have been stripped for track use.
The transistor is a Toshiba 2SD1460, it is screwed to the heat sink but the connections are all potted in epoxy so it would take a little work with a dremel tool to get to the connections but not impossible.
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just as ibadnsx and brian k said the transistor does get bypassed when on hi only and the resistance in the blower motor is usually always the cause either do to debris or dust/dirt causing drag on the bearings.If your buddy who lent you the control head still has his car it only takes about 5 minutes to switch out the transistor.good luck
Re: Blower Power Transistor--outcome
I bought a replacement power transistor (cross-referenced by two websites), used a roto-rip to dig the old transistor out of the epoxy and installed the replacement--it did not work. Broke down and bought the part from Honda for >$200 and it worked. I would really have liked to report the $16 part worked but it did not for me.
I bought a replacement power transistor (cross-referenced by two websites), used a roto-rip to dig the old transistor out of the epoxy and installed the replacement--it did not work. Broke down and bought the part from Honda for >$200 and it worked. I would really have liked to report the $16 part worked but it did not for me.
Joe
Can I get the bad power transistor you have. I would like the figure out what the problem is so I can provide repair service on these in the future.
PM me, Thanks
Can I get the bad power transistor you have. I would like the figure out what the problem is so I can provide repair service on these in the future.
PM me, Thanks
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Sure--I'd like to know too--sent PM.
Joe Gliksman said:
I will check it out and let you know, not many of these fail but replacing the transistor is a much cheaper than buying the whole assy.
Briank said:
Got it today, looks like there is a thermal fuse hiding in the assy. that is blown. The old transistor looks like it may be shorted which would have taken out the fuse.
Hi Briank - this would be great to photo-document to show where the fuse is so us future failure victims can fix it on the cheap.
Joe, sorry you had to bite the big one, but at least you didn't pay a dealer to fix it. I'm guessing the dealer would have wanted a grand.
Joe, sorry you had to bite the big one, but at least you didn't pay a dealer to fix it. I'm guessing the dealer would have wanted a grand.
Well, I guess I did better than going to the dealer, but I hate to think I spent $200 for the assy. when it was a fuse--especially after going to the trouble of finding the cross-referenced power transistor--digging out the epoxy, soldering, etc. etc. I saw the fuse--thought it was a diode or resistor or something--a learning experience.
NSXBill2 said:
Yes but 95% of the time it the control board and not the transistor.
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Joe Gliksman said:
Joe
The repaired power transistor assy. is on its way back to you. With the replacement of the thermo fuse it works just fine now. Thanks for providing a guinea pig for me to work on. :smile:
Hi Brian - I helped Joe trouble shoot his car, and we swapped his "repaired" assembly (the very one he sent to you) into my car to see if the problem followed the assembly, which it did. What is puzzling is the fact that we checked continuity from the plug to the transistor pins - all tested OK. If there was a bad fuse in the circuit, shouldn't we have seen an open continuity in one of the wires?
Check for continuity between the blue wire to case of the transistor. The fuse is buried inside the assy.
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- Joined
- 19 August 2008
- Messages
- 330
Brian,
What was this thermal fuse that you replaced in the NSX transistor assembly? I think mine may be the blower transistor that failed since the board was recently repaired by you and also sent back to verify full functionality.
I found the transistor part number here:
http://nsxprime.com/forum/showpost.php?p=1458359&postcount=1
What was this thermal fuse that you replaced in the NSX transistor assembly? I think mine may be the blower transistor that failed since the board was recently repaired by you and also sent back to verify full functionality.
I found the transistor part number here:
http://nsxprime.com/forum/showpost.php?p=1458359&postcount=1
As noted above the "fuse" is built into the power transistor assy. Its also potted so its going to take you some time with a dremel tool to get to it. If you find its truly blown the motor should also be replaced since a bad motor is what causes it to fail. You are welcome to send it to me and I will confirm that is is truly bad.
- Joined
- 19 August 2008
- Messages
- 330
Just wanted to update everyone on the climate control fiasco....it is working like a charm now!
The most recent culprit was the transistor....due to something I did. When I first bought the car, I took apart the blower motor and transistor to "diagnose" it....when I put the transistor back together, there is a screw/nut that holds the thermal fuse into the circuit and I forgot about it when I re-assembled it.
But I'm glad I sent my board to Brian b/c that was DEF the initial problem....and the subsequent problem was my own doing
The most recent culprit was the transistor....due to something I did. When I first bought the car, I took apart the blower motor and transistor to "diagnose" it....when I put the transistor back together, there is a screw/nut that holds the thermal fuse into the circuit and I forgot about it when I re-assembled it.
But I'm glad I sent my board to Brian b/c that was DEF the initial problem....and the subsequent problem was my own doing
