Write-Up: Blower Motor Control Module Replacement

As far as repairs are concerned, it doesn't get any easier than this.

Tools Needed

- 7mm socket or wrench
- 5.5mm socket or wrench
- Possibly a Phillips screwdriver

The BMCM is located on the passenger side floor in the heater box. You will start by removing the 2 screws with the white arrows. They will be either 7mm or Phillips head. After removing the screws, that panel pulls straight down.


Now you can see the Blower Motor and the BMCM (white arrow). There are two 5.5mm screws holding the unit in. Simply unplug the 2 connectors, and remove the 2 screws. It will then slide down and pull out.



Reverse the procedure and your done! Very, very simple, yet pricey repair.

Great write up!

When I pulled the car out of a 2 year storage the fan was stuck on high whenever the battery was connected, fried.

Being pressed for time and $$ I found a caddy blower module on my used parts shelf, plugged it in, it worked even though there was one additional pin.

Next problem was mounting ,close but wrong shape, I took the bench grinder to it figuring I had nothing to loose, well it fit minus one bolt.

Perhaps I could save someone $$ with my experience.

98inSFl wrote:

Great write up!

When I pulled the car out of a 2 year storage the fan was stuck on high whenever the battery was connected, fried.

Being pressed for time and $$ I found a caddy blower module on my used parts shelf, plugged it in, it worked even though there was one additional pin.

Next problem was mounting ,close but wrong shape, I took the bench grinder to it figuring I had nothing to loose, well it fit minus one bolt.

Perhaps I could save someone $$ with my experience.

...might help if you could say what year caddy that was out of. Someone might spot one at a pick-n-pull.

Albertj

If I knew....

Several years ago I was collecting blower modules from the junkyard for a used caddy,it was unmarked on a shelf, likely to be mid to late 90s, this is one of those GM pieces that seems to be everywhere at the junk yard , I used it because it looked similar.

I think i said this in another thread, but i replaced mine from a 97 Olds Aurora from a local junk yard for $10. It works great i didn’t notice any extra pins or anything different, but maybe they made them more durable or something.

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.

Cmurphy wrote:

I keep thinking about the name and its just a resistor, i'm going to pull it later today and look for a cheap way of fixing this

Not gonna happen. Good luck though........

I recently had the blower motor on my 1997 Riviera stop blowing. I did some research and found out it's often the blower module (which I've had people also call a resistor pack), and that the part was about $220 and impossible to find.

I grabbed one out of a 1995 Riviera at a scrap yard, changed it out, and still no love from the blower. I did some more research and found out some places that list compatibilities show that the part for a 95 is different from a 97. So what I'm trying to decide now is if the two should interchange, or if maybe the one I got from the scrapyard is bad, or if it could be something else entirely. Before it went out, it went on and off intermittently, if that helps. A garage checked it out and said there's just no power going to the blower motor, but finding out more would be $60 for a diagnostic.

Just bought this, and in the past month I've had to replace both front wheel bearing assemblies, the belt and the oil sending unit, so I'm hoping to be able to do this myself without any more high costs. Any help would be appreciated!

Part number for 95-96 is 12368388, 97-99 is 52470336, indicating they are different modules. Even if the 95-96 part fits, I would not expect it to work correctly. When I had this problem (intermittent HVAC operation), I replaced with a used module from the same year, and this fixed the problem.

AA wrote:

Part number for 95-96 is 12368388, 97-99 is 52470336, indicating they are different modules. Even if the 95-96 part fits, I would not expect it to work correctly. When I had this problem (intermittent HVAC operation), I replaced with a used module from the same year, and this fixed the problem.

I would contact Ed Morad http://moradpartscompany.com/. He should have a working used module for a good price. I bought an door actuator for the HVAC from him and it worked great.

Guys, I said earlier in this thread a module out of a late 90s caddy has one more pin then needed, needed trimmed but seems to work EXACTLY as the correct unit. 10,000 miles and counting since I did this in my daily driver a 98 riv.

jsm, you describe a failing motor not a failing module, rap your motor with a hammer handle a few times to stimulate things, cycle the key and try again.

Good point, Ed.

jsm, do you still have your 1995-96 module? Can you take a picture, or give any information from the device case? We may be able to compare to the newer part in order to confirm what Ed is saying.

Thanks for all the tips so far, guys. I went ahead and just bought another salvage replacement, this one from a '97 Aurora (exactly the same part number and everything), and still no go. So I'm trying to decide where to go from here.

Ed, I'm going to give that a shot tonight, but I had a garage look over it just a little, and they said it's definitely an electrical problem of some sort (I guess they tested the motor). I've been using these guys through three different cars now, so I'm trusting them to not get it wrong - though I'm going to feel pretty dumb if I'm wrong.

Did you bother to check the 10A HVAC Blower Motor Fuse in the IP fuse block??

Yep. The garage said they had, but I checked just to be safe since it's an easy thing to look at. I checked the one that's on the inside, on the driver's side of the car. That's good, unless there's another fuse or relay I don't know about.

jsm wrote:

Yep. The garage said they had, but I checked just to be safe since it's an easy thing to look at. I checked the one that's on the inside, on the driver's side of the car. That's good, unless there's another fuse or relay I don't know about.

There is another. There is a 30A HVAC Blower Motor Fuse under the rear seat as well.

Good to know! Going to go check that right now, then. It'll actually be the first time I've looked at the stuff under there (probably should have done that before at some point just to see it).

EDIT: Just realized that might not explain the stopping/starting it did before it went out, but I'm going to check it anyway.

Well, if all the fuses are good, it's possible the BMCM you got is wrong (or inop), or, worst case scenario, the HVAC unit took a dump. I doubt it's the HVAC unit.....

Fixed it! I'm an idiot.

Remember I said, either here or in my intro post, that I haven't worked on cars in a while? Well, apparently, when I told the garage to just leave the panel open because I was going to try to replace the resistor myself, they didn't get one of the cords to the blower motor all the way clamped in. Looked OK, but when I started wiggling stuff, it slipped out. So I plugged it back in, and it worked.

So it was definitely the resistor. And I (might) have a spare now, since the one from the '95 might possibly have worked. If anyone ever has trouble finding one, let me know!

Thanks again for all the help. I'll try to contribute what I can to the boards moving forward, but, if you just read the above part, you probably wouldn't want my help.

LOL!!! Glad you found it man!

nice, i had the same problem yesterday with the fan goin slow, fast, off, then back on again... whent out to goto work 20 min ago and no blower motor at all so as soon as my windows defrost ill have to hit the junk yards for a BMCM.

I changed mine out this past summer with a replacement from Ed Morad. The blower was cutting in and out and it the replacement fixed the problem, or so I thought. Yesterday it started to do it again. Is it a coincidence that the used replacement just went bad a few months later or could something be killing it?

Coincidence. Whose to say the used one was much better than your old one?

deekster_caddy wrote:

Coincidence. Whose to say the used one was much better than your old one?

\

Thats what I was thinking, but just wanted to make sure before I ordered a new one. I found one on Amazon for $100, so I will get that one.

My car started doing this today. Can't complain since the weather has been abnormally warm.

If you don't mind me asking, how much did the replacement from Ed Morad cost you?

I'm thinking of going that route since there aren't many Riv in the yards around here.