fan still on high even without ccu???help

[joboo]

So I think my ccu is hooped so it's on its way to BrianK. But today I drove the car the first time since I have the ccu removed and the fan is still blowing on high. Anyone have any ideas? I have looked at FAQ and searched but it turn up something different thanwhat I have read about. Could it be a/c fan control / power transisitor thing? Please help. Thanks.

 

[chang99]

Power transistor shorted and you can not turn off the ac unit. Do not try to replace the transistor by yourself cuz Acura made it such way you can not take it apart.

 

[Larry Bastanza]

You also may find a bad fan relay, maybe Escosse will comment, this is his forte.

HTH,
LarryB

 

[D'Ecosse]

.. maybe Escosse will comment

Not sure who that guy is but I'll try to help <!--StartFragment -->

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The 'hot' side of the blower motor is enabled by ignition via the 'blower motor' relay;
(Note - there is also a 'blower motor high' relay - not the same function, more on that in a second)

The ground side return of the motor current is what makes it run in one of two ways

- by the transistor (to control speed) The transistor is like variable resistor if you will and will either open up & allow more current through, or close down & restrict it - if transistor is shorted, then it will allow the max current through & run full speed. The transistor normally needs the A/C controller module to turn it on or off but if it is shorted then motor will run with ignition.

- However the second mode is that the transistor is by-passed by the 'blower-motor high' Relay in the under-hood relay box 'A'. The relay is also normally controlled by the A/C controller but the contacts can certainly 'stick'.

First step would be to remove the 'blower motor high' relay & see if blower motor stops:
If it does then you have sticking relay - if it doesn't, bad transistor it would appear!

.

 

[joboo]

Thank you D'Ecosse I will look into the blower motor high relay and try to narrow it down to that I hope..

 

[joboo]

OK so I removed the blower motor high relay and the thing still blows high.

-I removed the blower relay and the blower stopped obviously.

- So now I will try the transistor.
-Is it the ac/ fan control power transistor that Dali sells for $200?

Is this the part# 79340-SL0-A01 power transistor? Thanks.

 

[D'Ecosse]

...Is this the part# 79340-SL0-A01 power transistor? Thanks.

Yes, that's the correct part #.
Sorry for your results - I would say that's definitely the problem then

There is a TSB on that failure on early cars - http://www.nsxprime.com/FAQ/Reference/tsb/92-007.htm

Contrary to earlier comment, shouldn't be a big deal to replace it. (the assembly anyway - not sure if that's what the previous poster meant)

Note in the TSB they recommend replacement of the motor too.
79310-SL0-A01
Motor is also about $200 so $400 for both parts!

If you do have an early car in that range, I would suggest to follow the advice - those transistors are expensive 'fuses' if the motor is causing the problem!

You might try a breakers (like Erz) to see if you can get the motor assembly complete with the transistor? Or check through the 'parts for sale' Marketplace forum - you will find a number of guys breaking cars in there, even if the blower motor is not specifically listed, worth a PM.

I'm sure replacement of the transistor itself (rather than the whole TR assembly from Acura) would be much, much cheaper - & I don't know why it wouldn't be possible. However I don't know what model transistor is required though. Perhaps if you can go ahead & remove it we can tell if that's a feasible idea.

p.s. incidentally once you disconnect it you can measure with an ohmmeter to validate that transistor actually is shorted before you commit to purchase.

 

[Shaun Ray]

If I recall, there is a thread or two on the idea to replace the transistor, however I don't recall a good outcome. Still, I believe a transistor number was identified in one of the threads for what it's worth.

 

[D'Ecosse]

If I recall, there is a thread or two on the idea to replace the transistor, however I don't recall a good outcome. Still, I believe a transistor number was identified in one of the threads for what it's worth.

http://www.nsxprime.com/forums/showthread.php?t=43683&highlight=blower+motor+transistor

I love our search engine!!!!!

Looks like The transistor is a Toshiba 2SD1460 - Briank has replaced one before as you will see from the thread linked above. Since he's doing your CCU you should contact him about this repair also - but also note the comment re the motor.

 

[Briank]

I have never heard of a power transistor shorting on but unpluging it and checking with an ohm meter will quickly prove or disprove if it's shorted. Heck just unpluging it will prove if its shorted.

 

[chang99]

Yes, the transistor is made by Toshiba. My previous comment on not to try to replace this transistor yourself. Honda made it where you can not remove this transistor from the housing. If you do, you will break it and the best electrician in the world can not repair it. The reason this transistor short out is because the blower motor runs on a pair carbon brushes just like alternator. After years of usage, the carbon dust build up in the blower motor that will cause excessive current draw on this transistor. When you replace this power transistor, I suggest to take out the complete blower motor housing. Remove the blower motor cover and take a deep breath. No, I meant to say take a deep breath before removing the blower motor cover. You can take this blower motor to any electronic shop and replace two new brushes.

 

[D'Ecosse]

That sounds good theory regarding the failure mechanism - the only concern I have is, the TSB was actually released in 1992 and only affected those cars prior to a certain vin, which means they changed things thereafter - it looks like they made a change to the motor design as well as the transistor (as evidenced by the part about ensuring the replacement motor has a white dot on the plug - presumably to easily identify a later one)
Also there doesn't appear to be any wholesale evidence of motor or transistor failures in the post 92 cars to my knowledge anyway.
So - yes, maybe cleaning would help but the suggestion remains that it could happen again with the original motor. If economy was a concern, I would probably personally rather buy a used motor assembly (assuming one could be found) than replace just the transistor assembly on an original affected pre 92 unit. I wouldn't know if the commutator design changed &/or the brushes & you might think that if Honda could have simply replaced brushes rather than whole motor under the TSB they might have gone that route? Don't get me wrong - I think there's a reasonable chance it might be ok, maybe at $20 for a transistor, but $200 that's an expensive fuse if it's not!

 

[joboo]

OK- as per TSB 92-007 I have ordered the blower & transistor. My car is in the range of the TSB & Brian has checked over the CCU and it's fine. I have also checked the relays and it still blows high with the blower high relay removed. So , I will let you know if the TSB repairs fix the problem.

 

[Briank]

I will be real interested in knowing if replacing the transistior and blower will fix your problem. The problems you are having are nothing like the TSB problem where a bad motor damages the power transistor assy.

 

[joboo]

As Brian-I am also interested in seeing if the above fixes the problems. If anyone has any other input please step up. Thanks.

 

[D'Ecosse]

OK- as per TSB 92-007 I have ordered the blower & transistor. ...

Did you at least follow Brian's suggestion & unplug the transistor first to validate whether that was the source of the current return?

 

[joboo]

No- I did not. I figure if I'm going to take it apart that I might as well replace it with new parts. Thanks- I will keep posted

 

[Briank]

Did you at least follow Brian's suggestion & unplug the transistor first to validate whether that was the source of the current return?

:wink:

 

[joboo]

SO Guess what? I just replaced the blower motor & transistor as per TSB above & POW SURPRISE!!! The blower has now stopped blowing on full...YEAH!!! Now I have to wait until I get my CCU back from Brian to see if it all works out. I hope it's all good. Thanks to all that have helped out. I wouldn't even know where to begin if it wasn't for PRIME members. I will keep posted when I get my CCU back.

 

[Hugh]

SO Guess what? I just replaced the blower motor & transistor as per TSB above & POW SURPRISE!!! The blower has now stopped blowing on full...YEAH!!!

I should hope the hell so considering you have all new hardware.

 

[Larry Bastanza]

Not sure who that guy is but I'll try to help <!--StartFragment -->

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Lazy bastard I am, I used my tired memory to remember the spelling LOL......

 

[D'Ecosse]

Lazy bastard I am, I used my tired memory to remember the spelling LOL......

I've been called worse!
When talking about you in our local circle I always want to call you Larry Bartholomew (who is a guy at work) - both begin with Larry Ba and oldtimer's disease makes then the same. :biggrin: