Name : Scott Location : Macomb, Michigan Joined : 2010-02-24Post Count : 4316 Merit : 185
Subject: Re: Write-Up: Blower Motor Control Module Replacement Wed Feb 19, 2014 8:33 am
The only Head schematics I have are what I've posted for you, and one's for the Sunload sensors and passenger heater control. You should be able to diagnose your problem with what I've given you so far.
J. Chris Davis Aficionado
Name : Chris Davis Age : 43 Location : Dixon, IL Joined : 2010-04-14Post Count : 1008 Merit : 19
Subject: Re: Write-Up: Blower Motor Control Module Replacement Thu Feb 19, 2015 2:00 pm
Great write-up. Helped me figure out where this was and diagnose it as the problem. Took me about a half an hour to get changed out and now I have blowing heat again. Man was it cold last night and this morning with no heat blowing in the car.
chitown_riv98 Fanatic
Name : Ruben Age : 43 Location : Illinois Joined : 2008-03-10Post Count : 399 Merit : 4
Subject: Re: Write-Up: Blower Motor Control Module Replacement Thu Feb 19, 2015 10:35 pm
J. Chris Davis wrote:
Great write-up. Helped me figure out where this was and diagnose it as the problem. Took me about a half an hour to get changed out and now I have blowing heat again. Man was it cold last night and this morning with no heat blowing in the car.
I went thru a winter in Chicago with no heat due to a blower module out in the riv. It really sucked. I had to scrape inside the car. That's what got me to rivperformance
stan Expert
Joined : 2007-07-01Post Count : 2558 Merit : 12
Subject: Re: Write-Up: Blower Motor Control Module Replacement Fri Feb 20, 2015 12:06 am
...wow...in Chicago with no heat Ruben?......man.....
chitown_riv98 Fanatic
Name : Ruben Age : 43 Location : Illinois Joined : 2008-03-10Post Count : 399 Merit : 4
Subject: Re: Write-Up: Blower Motor Control Module Replacement Fri Feb 20, 2015 11:13 am
Yep. I would get to work after an hour drive with hypothermia. I figured it out finally and got a new module at the dealer to install. Its a pain working under the dash to replace it. Thanks to this forum I figured out the problem
charlieRobinson Expert
Name : Charlie Age : 39 Location : Knoxville, TN Joined : 2011-05-17Post Count : 3924 Merit : 31
Subject: Re: Write-Up: Blower Motor Control Module Replacement Mon Mar 02, 2015 9:07 pm
My turn... First start yesterday morning and I had no air; warm or cold. No signs of life from the fan motor.
Thanks, Scott, for the write up.
AA Administrator
Name : Aaron Age : 47 Location : C-bus, Ohio Joined : 2007-01-13Post Count : 18452 Merit : 252
Subject: Re: Write-Up: Blower Motor Control Module Replacement Mon Mar 02, 2015 11:31 pm
If you can wait for it, try finding a used OEM part - mine was $30. These modules either go bad or last forever, it seems. If you buy from RockAuto: $130, GMparts Direct: $150, dealer: $290.
'70 Ninety-Eight Holiday Coupe 455cid • 116k miles ^^^ SOLD ^^^
Abaddon Expert
Name : Scott Location : Macomb, Michigan Joined : 2010-02-24Post Count : 4316 Merit : 185
Subject: Re: Write-Up: Blower Motor Control Module Replacement Tue Mar 03, 2015 8:36 am
charlieRobinson wrote:
If I'm not getting any air or sounds at all, it's most likely the blower motor, right? And not the control module?
Didn't I specifically tell you to put 12v to the Blower Motor? (not in this write-up) You can do it right in the car without removing it. I've used a Battery Jump Box with some jumper wires before....
Or better yet, get yourself a 194 marker light socket with a bulb. Unplug the blower motor. Put the wires of the light socket into the connector for the blower motor. Turn the heat on HIGH. The bulb should light up BRIGHT. The lower fan speed you go, the dimmer the bulb will get. This would tell you if the BMCM is functioning or not. Or you could use a Voltmeter. 12V being HIGH setting, roughly 6V being LOW, with an even "ramp" in between.
RobbieAG likes this post
AA Administrator
Name : Aaron Age : 47 Location : C-bus, Ohio Joined : 2007-01-13Post Count : 18452 Merit : 252
Subject: Re: Write-Up: Blower Motor Control Module Replacement Tue Mar 03, 2015 8:45 am
Good idea testing the motor with 12v. Then do the lamp test on the module to rule out wiring/fuse/climate control as issue.
'70 Ninety-Eight Holiday Coupe 455cid • 116k miles ^^^ SOLD ^^^
charlieRobinson Expert
Name : Charlie Age : 39 Location : Knoxville, TN Joined : 2011-05-17Post Count : 3924 Merit : 31
Subject: Re: Write-Up: Blower Motor Control Module Replacement Sun Mar 08, 2015 12:05 am
I flew over to Psycho Sexy's hideout today.
Swapped out the BMCM from his parts Riv and sha-blam; air system is back online.
MONTANARIV Special
Name : Todd Klietz Joined : 2018-06-01Post Count : 2 Merit : 0
Subject: Re: Write-Up: Blower Motor Control Module Replacement Sat Jun 02, 2018 12:23 pm
Hi all - my fan in my 97 just stopped working at any speed driving out of the parking lot. Checked fuses, all good. Guy at NAPA whose owned 3 (2 '95s and a '99) said its likely the blower motor or the resistor. He had the blower motor so figured I'd try that first. What a PITA it is taking the blower out without removing the module first! Ah well, live and learn. Ended up having to remove the module anyway as I couldn't unhook the wires from it to let the motor drop. And it turns out, its not the blower anyway. GM module on order from Rock Auto for $120. Thanks for all the writeups - just like to recommend that if anyone needs to replace the blower motor, pull the module first - will make life much easier - cheers!
LARRY70GS Aficionado
Name : Larry Age : 68 Location : Oakland Gardens, NY Joined : 2007-01-23Post Count : 2193 Merit : 150
Subject: Re: Write-Up: Blower Motor Control Module Replacement Thu Aug 22, 2019 2:12 pm
Guys, In case anyone is having a problem with their blower motor speeds, Rockauto is having a wholesaler closeout on on the BWD/Niehoff RU1234, which is the blower motor module for the 98-99 Riviera. It's only 23.79! All the other choices are 100.00 or more. They have 5 left. I figured what the hell, for 23.79, I'll order it.
I usually leave my climate control on Auto and just select the temperature I want. I first noticed a problem this past winter as the blower didn't come on when it should have. Usually when the engine warms up sufficiently, the blower activates and all is well. This time, it didn't come on until very late and then it stayed on. As I started using the A/C this Spring, the blower would come on full speed, then quit, and then randomly oscillate between low and higher speeds, then quit, then repeat. About 5 minutes into my trip, it would stay on, and occasionally quit, then start again. This solved my problem. Box says Made in the USA.
_________________ 98 Riviera SC3800 All stock except gutted air box. 1970 Buick GS455 Stage1, TSP built 470BBB, 602HP/589TQ Best MPH, 116.06 MPH, Best ET, 11.54 https://www.youtube.com/watch?v=UHCda-t_Jls https://www.youtube.com/watch?v=sfT2tEO4XcU
albertj Master
Name : Location : Finger Lakes of New York State Joined : 2007-05-31Post Count : 8687 Merit : 181
Subject: Re: Write-Up: Blower Motor Control Module Replacement Sun Jul 19, 2020 11:43 pm
AA wrote:
It's a transistor - that appears to work as a motor speed controller for the blower motor. Printed on the component:
M (Motorola) S141042 MEXICO 9637
You'll need to identify it as NPN or PNP or other transistor type, then match or exceed the rated wattage and provide an equal or better performing heat sink.
I opted to buy the part from a yard for $30 - has lasted over 150k miles so far.
Update -
SJ41042 is the 'industry' part number for this semiconductor. The can is available but price varies wildly. I may try repairing mine if I can dismount it w/o destroying it.
Jack the R Master
Joined : 2007-01-16Post Count : 8072 Merit : 105
Subject: Re: Write-Up: Blower Motor Control Module Replacement Mon Jul 20, 2020 6:36 pm
LARRY70GS wrote:
Guys, In case anyone is having a problem with their blower motor speeds, Rockauto is having a wholesaler closeout on on the BWD/Niehoff RU1234, which is the blower motor module for the 98-99 Riviera. It's only 23.79! All the other choices are 100.00 or more. They have 5 left. I figured what the hell, for 23.79, I'll order it.
Aaaaaand they're gone!
LARRY70GS Aficionado
Name : Larry Age : 68 Location : Oakland Gardens, NY Joined : 2007-01-23Post Count : 2193 Merit : 150
Subject: Re: Write-Up: Blower Motor Control Module Replacement Mon Jul 20, 2020 6:44 pm
1 month short of a year too late. That was a deal.
_________________ 98 Riviera SC3800 All stock except gutted air box. 1970 Buick GS455 Stage1, TSP built 470BBB, 602HP/589TQ Best MPH, 116.06 MPH, Best ET, 11.54 https://www.youtube.com/watch?v=UHCda-t_Jls https://www.youtube.com/watch?v=sfT2tEO4XcU
albertj Master
Name : Location : Finger Lakes of New York State Joined : 2007-05-31Post Count : 8687 Merit : 181
Subject: Re: Write-Up: Blower Motor Control Module Replacement Mon Jul 20, 2020 11:00 pm
I just installed a BMCM I pulled from a '99 Aurora today. Was having the intermittent fan full on/fan full off cycling that was said to indicate a dying BMCM. Also, I located sources for replacing the SJ41042. They are cheap (like $2 each) but to get that price I have to buy 6-10 of them ha ha. Also needed is silicone potting compound (the module is sealed with what appears to be dielectric silicone potting compound), it is something like $20 from Digi-Key. If I go forward with rebuilding the BMCM then I will likely post a write-up. Problem right now is kind of stupid - I can't find a spec sheet for the Motorola SJ40142. Thought I might have one in an old ARRL manual, but can't find that manual either. Before doing the write-up I want to check if there is a more readily available equivalent, or an upgrade.
For instance in the write up on the HVAC control head (the dash unit with all the buttons) I mentioned using better power resistors to upgrade the head's resistor bridge. When I re-did mine I used higher wattage/same value/narrower tolerance resistors meant for use in RF applications. The upgrade worked well; I have never had to mess with the resistors again, although I have removed the head twice to replace burned out light bulbs. In the same way, a component for the BMCM with the same functional characteristics but capable of handling more current would be nice, avoiding the failure, since the replacement requires an obsolete component. SO, if any of you happen to have such a spec sheet I'd be much obliged to you for having a look at it.
Albertj
Jack the R Master
Joined : 2007-01-16Post Count : 8072 Merit : 105
Subject: Re: Write-Up: Blower Motor Control Module Replacement Tue Jul 21, 2020 4:38 am
LARRY70GS wrote:
1 month short of a year too late. That was a deal.
Oops - didn't see how old your post was
LARRY70GS Aficionado
Name : Larry Age : 68 Location : Oakland Gardens, NY Joined : 2007-01-23Post Count : 2193 Merit : 150
Subject: Re: Write-Up: Blower Motor Control Module Replacement Sat Dec 24, 2022 2:37 pm
Well, the other day, as I was going to work, I noticed the blower motor changing speeds back and forth, and when I shut the engine off, you guessed it, the blower motor kept going. Had to pull the big 30 amp fuse under the rear seat to get it to quit.
Time for another blower control module at 100.00 +
_________________ 98 Riviera SC3800 All stock except gutted air box. 1970 Buick GS455 Stage1, TSP built 470BBB, 602HP/589TQ Best MPH, 116.06 MPH, Best ET, 11.54 https://www.youtube.com/watch?v=UHCda-t_Jls https://www.youtube.com/watch?v=sfT2tEO4XcU
Jack the R Master
Joined : 2007-01-16Post Count : 8072 Merit : 105
Subject: Re: Write-Up: Blower Motor Control Module Replacement Sat Dec 24, 2022 6:28 pm
How many have you been through?
LARRY70GS Aficionado
Name : Larry Age : 68 Location : Oakland Gardens, NY Joined : 2007-01-23Post Count : 2193 Merit : 150
Subject: Re: Write-Up: Blower Motor Control Module Replacement Sun Dec 25, 2022 8:58 am
Jack the R wrote:
How many have you been through?
Counting the original equipment, this will be the third one. This one only lasted a bit over 3 years. When Rock Auto had the closeout, I should have bought more than one. I didn't think they were this prone to failure.
_________________ 98 Riviera SC3800 All stock except gutted air box. 1970 Buick GS455 Stage1, TSP built 470BBB, 602HP/589TQ Best MPH, 116.06 MPH, Best ET, 11.54 https://www.youtube.com/watch?v=UHCda-t_Jls https://www.youtube.com/watch?v=sfT2tEO4XcU
Jack the R Master
Joined : 2007-01-16Post Count : 8072 Merit : 105
Subject: Re: Write-Up: Blower Motor Control Module Replacement Sun Dec 25, 2022 11:26 am
I'm still on my original AFAIK. I haven't changed it in 16 years of ownership.
albertj Master
Name : Location : Finger Lakes of New York State Joined : 2007-05-31Post Count : 8687 Merit : 181
Subject: Re: Write-Up: Blower Motor Control Module Replacement Thu Dec 29, 2022 8:20 pm
LARRY70GS wrote:
Jack the R wrote:
How many have you been through?
Counting the original equipment, this will be the third one. This one only lasted a bit over 3 years. When Rock Auto had the closeout, I should have bought more than one. I didn't think they were this prone to failure.
I wonder if you have an issue in the HVAC control head in the dash.
I am on my 2nd blower module. Changed the first one out for a junkyard unit. I have replaced the HVAC head twice - once for fried resistors and once again for my own convenience in refreshing the lighting.
Jack the R Master
Joined : 2007-01-16Post Count : 8072 Merit : 105
Subject: Re: Write-Up: Blower Motor Control Module Replacement Thu Dec 29, 2022 9:14 pm
Original HVAC head here.
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Subject: Re: Write-Up: Blower Motor Control Module Replacement