Heater Fan Motor Brushes

[drew]

See this thread: http://www.nsxprime.com/showthread.php?t=73009

I'm trying to clean and rebuild the heater fan. This is necessary to prevent transistor burn out and motor replacement. Costing several hundred dollars minimum.

The motor insides were extremely dirty and the fan was rather dusty. Otherwise, the motor is extremely well made.

The problem is that I'm having a very difficult time locating new brushes.

The brush size is 8mm x 8mm x ~16mm with the contact on the side about 3.5 mm from the edge. (inches: .314in x .314in x .62in) They are made out of either silver graphite or electro-graphite.

Does anybody have any sources for such a part?

I've located a service that will build any brush I want, but I need some additional brush orders to make it feasible...with 10-15 sets I can probably get it down to ~ $5/set. (anybody?)

I can't even determine the manufacturer of the motor, the logo is blue M with rounded corners, inside a rounded corner border. (Anybody?)


Any help or interest is appreciated.

Drew


additional key words climate system fan motor p/n: 79310-SL0-A01 79310-SL0-A02

2005506 (some sort of p/n on motor)

 

[Briank]

Drew

You might whan to try http://www.helwigcarbon.com/ and see if they can help you.

 

[SWFL_NSX]

Bumping this back up. My HVAC blower is on full blast regardless of the setting of the CCU, or even if the CCU is powered on.

I'm going to replace the transistor and the fuse that is potted in there but also want to fix the root cause.

@drew , did you ever find the correct brushes or have any other info on rebuilding this motor?

 

[drew]

I did not. The MoQ was too high and not enough interest.

I do recommend cleaning the insides of the motor though...it was caked with carbon.

One can find brushes on AliExpress. If exact size cannot be found, get one that is slightly oversize and sand/file it down to dimension...should work fine.

And 16 years later I have discovered that the M is for Masushita.

 

[Briank]

Bumping this back up. My HVAC blower is on full blast regardless of the setting of the CCU, or even if the CCU is powered on.

I'm going to replace the transistor and the fuse that is potted in there but also want to fix the root cause.

@drew , did you ever find the correct brushes or have any other info on rebuilding this motor?

The blower transistor normally fails open so the blower running full speed all the time could be a problem with the blower high relay being stuck or being turned on because of a control issue.

 

[SWFL_NSX]

The blower transistor normally fails open so the blower running full speed all the time could be a problem with the blower high relay being stuck or being turned on because of a control issue.

Hmm-I thought when the transistor failed it would cause the blower to run at full speed all the time regardless of CCU setting-which is the symptom I have. I'm relatively sure it's not the CCU board as you repaired it in late 2018.

1. Is checking the blower high relay as easy as swapping a working/identical relay in and seeing if the problem goes away?
2. If the blower high relay is fine, how do I check for other control issues?

 

[Briank]

Hmm-I thought when the transistor failed it would cause the blower to run at full speed all the time regardless of CCU setting-which is the symptom I have. I'm relatively sure it's not the CCU board as you repaired it in late 2018.

1. Is checking the blower high relay as easy as swapping a working/identical relay in and seeing if the problem goes away?
2. If the blower high relay is fine, how do I check for other control issues?

I have never heard of a blower transistor shorting on, it can be easily un plugged to confirm its not the issue. For the blower high relay if unplugging it stops the fan then the next question is it stuck on or being sent a signal to to be on. If its being powered on your should be able to hear the click when you unplug/plug it in. If its not clicking then its stuck on, if it clicks them its being told to turn on.

 

[Old Guy]

Page 22-92 of the 1991 service manual describes the relatively simple test for the relay. Replacement by substitution of a known good relay will also work. Check the service manual supplement (or the Electrical Trouble Shooting Manual) for your specific model year. Honda moved the relays around during the production run so the Blower High relay (different from the Blower relay) may not be where the 1991 service manual shows it. Also, check the relay socket for damage. If the socket over heats the plastic can melt allowing the connections to come into contact although normally this just results in a permanent open circuit).

I agree with Brian K that the more normal mode of failure for transistors is to go open circuit. However, shorting from collector to emitter has occurred, though much rarer. With the transistor unplugged, using a digital multimeter it is technically easy although awkward as hell to check for a permanent short between the emitter and collector.

 

[SWFL_NSX]

Update on this. I replaced the blower high relay with a good used part from ebay and everything is back to normal.

It was cheaper to buy a pair of used relays and keep one in the glove box instead of buying a new one from Honda. Can't tell if parts are getting more expensive or I'm getting cheaper.

Thanks all!

 

[Old Guy]

Can't tell if parts are getting more expensive or I'm getting cheaper.

Yes

There is a local pick and pull that I visit on occassion. It is an interesting place because the probably 300 cars only stay on the lot for perhaps a year or so and then they get shuffled off to the steel mill right next door to be melted and turned into something else which provides for a relatively steady turn over. Sometimes when I am dreadfully bored it is interesting to troll the rows and examine the fresh carcasses (wow - that one is really smacked up good) and it is pretty clear that somebody is regularly going through and harvesting Denso, Siemens and Mitsu relays. Perhaps they have an EBay account and sold one to you.

I was talking to the operator of the facility and he said that they have someone who routinely goes through the lot and pulls fuses. I am having a hard time getting my head around the fact that there is a market for used ATO fuses. Perhaps he has a fuse fetish.