HVAC blower motor question

[SF944]

Climate cntrl fan only blows on high!

I've got one of the (apparently many) climate control issues:
"Blower motor only runs on high."

I've looked at the TSB on it (TSB #92-007), and it says that both the blower motor and the power transistor should be relpaced.
The cause is suspected to be "Contamination on the blower motor commutator ring creates a higer than normal current draw. This causes the power transistor to fail."

My question is, since my blower works (on high), does it really need to be replaced? Shouldn't a new power transistor do the trick? How do you prevent the "contamination" and what the
&%$* is a commutator ring?

Has anyone done this repair at home?

 

[SF944]

C'mon guys, I can't be the only one who's had this problem!


Mark at Dali said the transistor is $188.00 I didn't ask for a price for the blower motor yet, I'm affraid to..... So I'm hoping I may not need it...........

Any help appreciated.

 

[Ojas]

Well, I don't know for sure, but here it goes...

I suspect the contamination occured during the manufacturing process for the motor. The commutator ring is an internal part of the motor. I think the ring is connected to the shaft of the motor and makes contact with the brushes which are on the stationary (outside) part of the motor. The job of the ring and brushes is to get electrical current to the spinning part of the motor. Someone please correct me if I'm wrong.

Anyway, I'm in the same boat as you. I am going to replace both parts. As far as I can tell, It's the blower motor that's drawing excess current through the transistor, eventually causing the transistor to fail. I think you need to replace both parts. If you just replace the transistor, I bet it will work fine for a while, but will eventually fail.

BTW: MSRP on blower motor is about $235 (MSRP for the transistor is about $270). Good luck!

 

[NSXROX]

I'm glad someone posted this problem. I have the same symptoms. Hmmmmm ... spend $500 to have my blower work at normal speed, or just deal with a high speed fan. I think for now I'll spend the $500 on something else.

 

[Ojas]

Well, for 91-92 NSXs (models the TSB applied to), I'd be worried that not fixing this problem may eventually cause the climate control board (the black box behind the climate control display) to go bad. I know many folks have had their boards go bad. Many have been able to simply replace the old dried out electrolytic capacitors. That's one thing and may just be due to age.

However, a local NSX let me borrow two bad board he laying around. I thought I could just replace the caps, but on both boards, there is an additional component that is clearly burned out. It's DM11 and looks like a transistor or rectifier... marked "MA117 - 10". Okay, now I really am speculating, but: Perhaps running not replacing the blower motor and power transistor per the TSB, caused this component to fail. I say this because first motor worked fine at all speeds, then occasionally worked only at high, now when it does work it works only on high, but often does not even do that. I think at this point, the board (along with the motor and power transistor) has failed.

NSXROX, in your case (since you have a '96) I think the problem may be the board. The TSB came out in 92 and applied to 91-92 cars. So, Honda probably fixed this problem in later models. (At least, I'd hope so). Some great info can be found here.

 

[SF944]

Thanks for chiming in, folks.

It doesn't seem there is much of a concensus on the problem. The link that Ojas provided is full of interesting information, mostly:

Gerhard Langguth
LANGGUTH Electronics Inc.
711 East Parkway Inc.
Russellville, Arkansas 72801
(479)967-0873

Does anyone else have experience with Langguth?

I'm not sure of the relationship (if any) between the '91-'92 TSB and the bad capacitor problem.

OK, now how about a hackmechanic-jucket-redneck repair: I haven't taken the thing apart, and have little or no electronic no-how, but it seems to me that since it runs on high or off, couldn't a variable resistor be run in-line with the blower? Similar to the dimmer switch over your dining room table? (G0-ahead, flame away, I'm just not ready to drop $500 on this fix). In the immortal words of Mikey the Life-cereal kid: "I'm not gonna try it....you try it!"

 

[Ojas]

Good idea, but you'd need one bigass (ie high-wattage) variable resistor to dissipate the heat from the currrent drawn.

The dimmer switch for your household light is different in that it does not just dissipate the excess voltage in the form of heat. They uses some sort of high-voltage transistor to switch the AC current on/off at variable point in relation to the wave's zero-cross point.

You get points for thinking like a true ghetto mechanic! It takes one to know one.

Oh, one more thing: Assuming MJ can give you a similar discount on the motor, the cost for both parts should be about $350, which really is not that bad. It starts to suck when you have to buy the climate control board, which is an additional ~$600 (discounted price).

 

[SF944]

Hey Ojas --
I'll certainly take "ghetto mechanic" as a compliment!!

From what you've seen and read, do you think the blower motor/transistor fix would do it, or is the "only runs on high" possibly caused by the c.c.board?

I'd just hate to dump the cash (even at an-MJ price) only to have to continue to chase my tail.

--SF

 

[BadCarma]

Thanks for chiming in, folks.

OK, now how about a hackmechanic-jucket-redneck repair: I haven't taken the thing apart, and have little or no electronic no-how, but it seems to me that since it runs on high or off, couldn't a variable resistor be run in-line with the blower? Similar to the dimmer switch over your dining room table? (G0-ahead, flame away, I'm just not ready to drop $500 on this fix). In the immortal words of Mikey the Life-cereal kid: "I'm not gonna try it....you try it!"

David

 

[Ojas]

SF944, I hear ya. I wish I knew for sure. I've been reading up on this but must emphasize: I have minimal hands-on experience.

My best guess based on what I've read so far: If it's a...

• 93+ and only blows on high: bad caps on the board.
• 91-92 and just started blowing only on high: replacing blower motor and power transistor per TSB could solve the problem.
• 91-92 and has only been blowing on high for a while, but now quits all together: all three parts.

It seems hard to diagnose because the "bad blower motor/power transistor" and the bad caps have the same symptoms.

Anyone else have any ideas?

 

[BadCarma]

SF944, I hear ya. I wish I knew for sure. I've been reading up on this but must emphasize: I have minimal hands-on experience.

[*] 91-92 and has only been blowing on high for a while, but now quits all together: all three parts. [/list]It seems hard to diagnose because the "bad blower motor/power transistor" and the bad caps have the same symptoms.

Anyone else have any ideas?

I agree with this assessment so to sf944, spend the 500 now or you can wait and spend alot more later as it sounds like your not the hands on type
Best regards David

 

[tomc92bb000059]

I had the same trouble, and ended up buying both the blower and the transistor, to find out that the board was the problem. Took it to the dealer for a diagnostic, as I didn't trust myself, and then had to tell them what to check. Shoulda just lit 4 $20s on fire...
There are several threads that tell who you can send the board off to who will check and repair for about $100. I ended up buying a used entire control unit from ERZ Motors for about $400. Only problem with buying the transistor and motor is that since they are electrical, no returns allowed. Probably should have put back my original blower and transistor, but figured I would rather be safe than sorry.
If I were you, find someone with a known good transistor and motor, and switch out. It is about a 20 minute job, not that hard at all. Everything is right behind the spare tire. This will tell you at least at first if it is either of them. If not, got to be the board. Get the board, and if still no workee, buy the others. Good luck, and it's not that hard a fix, if you take your time and read the manual. Get to doing it, and any questions, just ask...

Tom

 

[BadCarma]

I had the same trouble, and ended up buying both the blower and the transistor, to find out that the board was the problem. Took it to the dealer for a diagnostic, as I didn't trust myself, and then had to tell them what to check. Shoulda just lit 4 $20s on fire...
There are several threads that tell who you can send the board off to who will check and repair for about $100. I ended up buying a used entire control unit from ERZ Motors for about $400. Only problem with buying the transistor and motor is that since they are electrical, no returns allowed. Probably should have put back my original blower and transistor, but figured I would rather be safe than sorry.
If I were you, find someone with a known good transistor and motor, and switch out. It is about a 20 minute job, not that hard at all. Everything is right behind the spare tire. This will tell you at least at first if it is either of them. If not, got to be the board. Get the board, and if still no workee, buy the others. Good luck, and it's not that hard a fix, if you take your time and read the manual. Get to doing it, and any questions, just ask...

Tom

944, this might be of some help. if you dont need to do this at least you will have an idea on the process diy or sent out to repair shop. hope for the best

http://www.nsxprime.com/forums/showthread.php?s=&threadid=20134

Best Regards David

 

[SF944]

Hey Tom,
your reply couldn't have been more timely, as I was just about to go ahead and order the blower and transistor.
If there is anyone out there in southern New England who would be willing to let me "borrow" their blower for an hour --- gee, that doesn't sound good ) please let me know. I'll probably post in the Northeast section in a couple of weeks.

David, thanks for the link, hopefully I won't need it....but it appears to be very helpful.

Thanks to everyone for the help. I'll post the solution when I find it. --SF