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5K views 22 replies 7 participants last post by  joescadillac 
#1 ·
Hello all!

I've finally located the source of my A/C problems to be the BMCM, and now I'm stumped. Where is it, and how do I replace it? I've looked under the dash, under the hood...I've searched the forums and found that it's a "one minute fix," so I get the feeling I'm missing something big. I bought the Haynes manual and it isn't quite doing the trick either. Do I have to remove the coolant hose (draining all my coolant? =/) to get the blower motor assembly out, or is it a simple swap outside of that? Help, please!!!

Nathan Amoth
'88 DeVille 4D
 
#2 ·
If you're talking about the BCM, it is the Body Control Module and does not require the draining of the coolant etc. I wish I could remember the exact location of it, but alas I cannot. I will post the info in the AM if nobody else pipes up with the info before then. I have all the info at work. :(
 
#3 ·
No, it's not the BCM (Body Control Module). I've already replaced a faulty one of those sucessfully. I need installation instructions for the Blower Motor Control Module. I also need to be told (in plain, non-automotive terms) where on Earth it is. I have the replacement part ready to install, I just need to know where and how. Thanks!

Nathan Amoth
 
#4 ·
nihonbound said:
No, it's not the BCM (Body Control Module). I've already replaced a faulty one of those sucessfully. I need installation instructions for the Blower Motor Control Module. I also need to be told (in plain, non-automotive terms) where on Earth it is. I have the replacement part ready to install, I just need to know where and how. Thanks!

Nathan Amoth
Hello Nathan, I just replaced my "Blower Motor Power Module" on my 87' Deville, it's the same as yours, the reason you can't find it is because the "Aluminum Heat Sink" is NOT visible when the unit is installed so just Look for the Two Plugs that are visible on the passenger side (TOP) of your firewall under the hood, there are FOUR 7mm mounting screws holding it in place > Unplug the two plug harness from the module, take the 4 screws out and lift it straight up. Just look for the Top of the module and you will find it. :spin:
 
#6 ·
SoundAdvantage said:
Hello Nathan, I just replaced my "Blower Motor Power Module" on my 87' Deville, it's the same as yours, the reason you can't find it is because the "Aluminum Heat Sink" is NOT visible when the unit is installed so just Look for the Two Plugs that are visible on the passenger side (TOP) of your firewall under the hood, there are FOUR 7mm mounting screws holding it in place > Unplug the two plug harness from the module, take the 4 screws out and lift it straight up. Just look for the Top of the module and you will find it. :spin:
Mike,

I just came inside from my garage, where I removed what I assume to be the Blower Motor Control Module. Mine had three 7mm screws holding it in place, two plugs on top (which fed into one bundle of wire), and upon pulling it out, there was a large aluminum heatsink underneath the black top with the screw holes. Is what I removed itself the blower motor control module? In the space the heatsink occupies, all I see is empty space and what looks like an aluminum air filter to the left. The part I ordered to replace my Blower motor control module looks similar, yet different. If you would like, I can upload pictures of both the part I removed and the part I ordered, and perhaps the area under the hood that is now barren from my removing things. Thanks!

Nathan
 
#7 ·
more information and pictures

This is far too confusing. I called the local Cadillac dealer and described to them the part I removed, and they verified that it was the blower motor control module. Upon calling the place I ordered my replacement from, they told me that the part # I gave them off the original part was for a radiator fan module. Yet upon giving a detailed description to the dealer, they told me I had removed the correct part, and had been shipped the incorrect one. Agh! Pictures, you all decide! I've posted the pictures (56kers beware) with descriptions and questions at my website, on the following URL.

http://www.amoth.net/cadillac

Please be quick! I've got a hurricane coming my way, and the sooner I fix the blower, the sooner I get defrosters!!

Nathan Amoth
 
#8 ·
Re: more information and pictures

That's the blower control module alright. And yes it has (3) screws not (4). At least my 91 has 3 screws. Just for future reference, the numbers you find on parts isn't always the part number. Sometimes it's a "mold" number which MAY be the same as another part number.
 
#9 ·
Re: more information and pictures

Katshot said:
That's the blower control module alright. And yes it has (3) screws not (4). At least my 91 has 3 screws. Just for future reference, the numbers you find on parts isn't always the part number. Sometimes it's a "mold" number which MAY be the same as another part number.

Okay, so the part I removed from the car is indeed the Blower Control Module? If so, I'm going to go purchase a new one from the dealership tomorrow, as my other parts vendor seems to be a bit confused =/. Thanks so much for your help, everyone! I'll be sure to post the details about my ride elsewhere, along with pictures. I'm sure you'll all appreciate it.

Nathan Amoth
 
#10 ·
Re: more information and pictures

nihonbound said:
This is far too confusing. I called the local Cadillac dealer and described to them the part I removed, and they verified that it was the blower motor control module. Upon calling the place I ordered my replacement from, they told me that the part # I gave them off the original part was for a radiator fan module. Yet upon giving a detailed description to the dealer, they told me I had removed the correct part, and had been shipped the incorrect one. Agh! Pictures, you all decide! I've posted the pictures (56kers beware) with descriptions and questions at my website, on the following URL.

http://www.amoth.net/cadillac

Please be quick! I've got a hurricane coming my way, and the sooner I fix the blower, the sooner I get defrosters!!

Nathan Amoth
I figured they sent you the wrong part Nathan, The part you removed and have in the pics IS the right part, and yes it has 3 not 4 7mm screws > i was mistaken on the 4, i should have just looked at mine on the car but i was refering to my Haynes manual and it showed 4 screws, but at any rate you pulled the right part so when you replace it let us know how it works ok. Thanx
 
#11 ·
Yay!

The correct part (and new harness) arrived this morning. The place I purchased it from originally overnighted both to me at no cost, and is paying return shipping on the other one. I'm just munching on a cookie now, waiting for the car to cool off before I go install it. Wish me luck!!!

Nathan Amoth
 
#13 ·
the Sandman said:
Good Luck! Let us know if it works.

*cries and does a mighty dance of joy*

IT WORKED! BY GOD IT WORKED!

The A/C is ICE COLD. And FAST.
The heat is warm within seconds, and oh so hot.
The fans work!
The defrosters work! Ha, I say, Ha to you, Hurricane!

Now my car's electrical system is in tip-top shape! "Operation Mack Daddy" (the name for the processes involved in pimping out my car) has begun! I'll be copying the list of tasks ASAP and posting them here. Yahooooooo!!!

Nathan Amoth
 
#15 ·
Hey Nathan, I know the feeling, My system was completely reworked last month ;) Im glad you fixed it >See what The Cadillac Forums can do, now if someone else you know has the same problem you had then you can "Spread The Love" :spin:
 
#16 ·
Would it be safe to assume this is the same issue in my 86 Brougham in which the fan works, the heat is coming out; but the fan is not being activated.


The same looking part as well? I did the same as he, looking deeper and deeper in the dash to no avail.

Thanks!
 
#17 ·
Spock said:
Would it be safe to assume this is the same issue in my 86 Brougham in which the fan works, the heat is coming out; but the fan is not being activated.


The same looking part as well? I did the same as he, looking deeper and deeper in the dash to no avail.

Thanks!
if you mean the different fan speeds do not work? but it stays at a constant speed, yes i would suspect the fan power module.
 
#18 ·
Yes, it looks the same. Its located underhood top of heater box on right side . Follow the wiring from the fan motor to it. Looks very similar, but I think it has a rather retangular top on it, not tapered like the e body cars. Once the screws are removed, lift straight up to remove. It's located there to help cool the heat sink attached to it. Air passes over it as it enters the heater box. Good luck, Bill.
 
#20 ·
carnut said:
Yes, it looks the same. Its located underhood top of heater box on right side . Follow the wiring from the fan motor to it. Looks very similar, but I think it has a rather retangular top on it, not tapered like the e body cars. Once the screws are removed, lift straight up to remove. It's located there to help cool the heat sink attached to it. Air passes over it as it enters the heater box. Good luck, Bill.
Thank you! This certainly puts me on the right track; here's it been so cold that I've only been able to get 20 min at a time to check it out before my fingers freeze. I shall try again tomorrow.

Again, thank you,

~Abbas
 
#21 ·
Spock said:
Would it be safe to assume this is the same issue in my 86 Brougham in which the fan works, the heat is coming out; but the fan is not being activated.


The same looking part as well? I did the same as he, looking deeper and deeper in the dash to no avail.

Thanks!
You say the fan works? but the fan doesn't work? Do you mean you've applied voltage to the fan motor and it spins? If thats correct, I still would suspect the blower control module.
 
#22 ·
carnut said:
You say the fan works? but the fan doesn't work? Do you mean you've applied voltage to the fan motor and it spins? If thats correct, I still would suspect the blower control module.
The fan does work yes, had tested it with the battery.


Now that it's hit minus 30 and my garage is unfortunately unheated, I'm getting by on hitching rides with other family members hehe. C'est la vie I suppose.
 
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