Jump to content
SAU Community

BCNR33 Blower Motor Resistor - Testing

itsforandres

By itsforandres,
in Car Audio & Electrical

 Share

Recommended Posts

itsforandres Enthusiast

itsforandres

Posted
Posted (edited)

hello!

does anyone have a schematic that shows how to test the blower motor resistor for the vac system? i believe the part# is 27761-15U00. I think the resistor is toast, but would like to be able to test it somehow before i embark on the journey to find a new one.

cheers!

27761-15U00

Edited by itsforandres
added tags
dbm7 Contributor

dbm7

Posted
Posted

G'day ... first up, I very much doubt that's a resistor network (as used also for this job), but the part# looks right. The description of 'power module assembly' looks to be nissanese for 'PWM driven, ground switched, DC motor speed controller'.... the circuit in the schematic kinda infers that's the case...

spacer.png

...with the transistor symbol appearing in the unit described here as 'Fan Control Amp(lifier)'....being driven by pin20 on the HVAC unit,  and a feedback signal on pin19 from the motor negative terminal for some reason (might be motor fault detection, maybe they detect commutator switching to determine motor revs as well, I dunno)... but if they are  counting commutator spikes, a bad segment (or really worn brushes) will throw a spanner in the works...

The motor itself will as said be brushed DC with segmented commutator, rated at 12VDC nominally ~ now-a-days I just unplug them, determine the positive wire, and hook them up to a variable power supply and find out how much current they draw, if they work etc etc ...you can also check for bad segments...ie; set the power supply up to feed 1volt @ 2amp max, then watch the wattage count as you slowly rotate the fan blower motor through a complete revolution ; any bad/dead segments will be clearly evident...some folks would just say determine the positive wire, and feed it battery voltage, and if fan spin, you've got a win...<grin>... well, at least that infers it should do something when plugged back in, and the HVAC unit commands it to run... and if it doesn't, you suspect the module, but you should check the PWM signal on pin20 is actually present, and if it is, blame the module ...

 

  • Like 2
GTSBoy Grand Master

GTSBoy

Posted
Posted

^ This is all good advice.

I can imagine that there's some passive components in the HVAC controller that run that PWM output that could die, or suffer bad solder joints. It can be worth opening it up, taking a schmooze around looking for swollen electro caps, evidence of liquid escape anywhere, tracks that have been hot, lifted, cracked, etc.

A DMM might not be suitable for seeing if the PWM output is pulsing. Might be too fast and too low voltage for a DMM to keep up. An analogue voltmeter might give a better hope. I use a handheld oscilloscope (<$100 from Aliexpress if you want something cheap). A DMM might see the voltage across the motor flicker. Otherwise, as above.

If you can successfully see PWM action, then the control side should be good. If you can't see it with what you have, you might need to step up the instrumentation used, as above.

Beyond that, and dbm7's advice on testing the motor directly, you're down to looking for broken wires, corroded connector pins, etc.

  • Like 1
itsforandres Enthusiast

itsforandres

Posted
  • Author
Posted
9 hours ago, dbm7 said:

Oops... I meant to include the connector  view...

spacer.png

BR/W - power from fuse

L/W - motor negative to fan control amp (and off to HVAC pin19)

OR/B - PWM signal (from HVAC pin20)

B --  ground

 

 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Dose Pipe Sutututu
      Borg Warner EFR Series Turbo's V 2.0

      By Dose Pipe Sutututu · Posted

      Looking at the photos, you could easily just drop this pipe and dump into atmosphere  Just 1 or 2 quick hits for data acquisition - if have a heat shield material and/or sheet metal, maybe just use wire/metal cable ties and attach it in a way to deflect heat from melting nearby wires.  
    • Matt Z
      SAUNSW - GTR Festival 2025 - Saturday 24th May

      By Matt Z · Posted

      2025 PRP GTR Festival - A Massive Thank You from SAU NSW! On behalf of SAU NSW, I want to extend a huge thank you to our incredible committee for all the hard work and dedication behind the scenes. You are the engine that keeps this club running smoothly! (hopefully an RB lol😆) To all our amazing volunteers who helped make the GTR Festival Sydney such a success, thank you for giving your time, energy and sacrificing your weekend sleep-ins. Your efforts did not go unnoticed and were absolutely appreciated by everyone. We also want to give a big shoutout to the workshops, trade stalls, and the awesome VIP's we connected with over the weekend. Your support means the world to us, and we’re so proud to be part of such a passionate automotive scene. We are looking forward to collaborating with you at our future events.  SAU NSW had our marquee up for two full days at GTR Festival, packed with merchandise, a sizzling members BBQ, and a chance to chat with the committee, sign up, and check out some hot Skylines on display from our members. It was incredible seeing so many smiles and genuine conversations, that's what we're all about! SAU NSW is more than just a car club... we’re building a community where you can make friends, share stories, and talk about anything RB related or not. 📸 Please post any cool pics you took at the GTR Festival in this thread! 📸 To our current members, thank you for your ongoing loyalty, and to all our new members... welcome to the family! We’re beyond excited to have you on board! Please ensure you are involved as much as possible within the club, and make the most of our exciting upcoming events. Here’s to more future events, thrilling drives, chill meets and good feeds! Let’s keep building something special. 💪🚗💨 Matt Zoumpoulis, President SAU NSW
    • GTSBoy
      Borg Warner EFR Series Turbo's V 2.0

      By GTSBoy · Posted

      Yes, well, keep in mind that the air is intake air, which equal boost + possible oil. If there is a fine deposition of oil/scunge that then gets hot and carbonises, it could look just like that. Probably shouldn't be leaking. Might just be normal for that product. Hard to know if it is relevant.
    • TurboTapin
      R32 GTST - 600KW+ RB28/CD009 Build

      By TurboTapin · Posted

      Wrapped up putting the motor back in today. I have a stainless flex turbo drain pipe like you see on cummins and that funny enough PRP started selling. I generally prefer these but sadly they come with a finite amount of times they can be bent before they snap. Took well over a week for a replacement to arrive.  I was able to prime the pump but I will more then likely wait until next friday to take it on its madden voyage. I also installed the nozzles for my direct port WMI setup but plugged the nozzle holders for now. I'll tube it with Swagelok SS tubing and fittings next chance I get. No rush, i'll be breaking it for a week or two anyways. 
    • Borci88
      Borg Warner EFR Series Turbo's V 2.0

      By Borci88 · Posted

      I could definitely do some logs without the VCT enabled for sure. I believe we tried it on the dyno and it still spiked but wouldn't hurt to try again and have the logs    I might be able to use some metal cable ties and hold the gate open entirely, I'd need to see about that one.   What do we think about these marks on the cap of the actuator? This is where the two parts push together where the diaphragm spring is. To me they look like air has been sleeping past?? Specifically talking about those black stains above the lower rim/lip. They can be rubbed away as if it's just an exhaust stain.  
×
×
  • Create New...