BCM Installation (Fan Blower Control Module) + Pics

[ixlr8]

Since this has been a topic of interest for quite a few people and no doubt will be for more in the future, as this is a common problem, I am posting some info and pics to help those who need it.

If you are reading this and are having a problem with your fan blower there are many posts regarding how to pinpont the problem, the most common being the blower control module malfunctioning. This part was in stock at 2 different Ford dealerships I called locally. The price was $51 and change.

The BCM is located on the passenger side directly behind the cam (valve) cover.

There are two 8mm screws that secure the module to the firewall plastic cover. Although the module is not difficult to locate, it is notoriously difficult to get a tool to the screws in order to remove them. I used a 3/8 ratchet with 8" extension, 3/8 to 1/4 adapter, 1/4"-3" extension, 1/4" universal joint and an 8mm socket. I also disconnected the outboard heater hose from the firewall, and disconnected the other heater hose where it snaked downward and attached to the tube it connects to. This allowed a lot more room to work once I pinned them out of the way.



Once the heater hoses were disconnected and I had the right tool for the job, I removed the harness and the screws securing the module.



When removing the harness from the module, you have to blindly squeeze the release clip on the inboard side under the harness and pull away from the module. I wished a had a picture (like the one below) of the clip before I got started so I could validate my assumption that this was the case.



Here is a close up view of the front of the new module with part number.



When installing the new BCM, a big challenge for me was getting the screws started in the firewall to secure the new unit. I couldn't really even get my fingers in to get the screws started. So I implemented an old trick that has served me well in the past - unless you have magnetic sockets(?) you may be interested....I used a small piece of electrical tape and wedged it between the screw and the socket to hold the screw in place so I could easily insert the screw in the tight area using the extensions. Works well in really tight situations! Once the screw is started the tape easily gives way when removing the tool.



The BCM is shown in the picture below, you can see the new white label on the one I installed and the heater hoses are reconnected.




This summarizes the removal and installation of the BCM. If you read this first you will have a good idea of what to expect when it comes time to replace your own.
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The BAD BCM - what went wrong???

I smelled something burning before my fan stopped working so if this module was in fact the culprit of the problem I wanted to see some carnage. Once I removed the plastic cover from the unit I saw what I had previously "smelled". That was all of the validation I needed. When I turned the unit over I could see where one of the terminals had burned the circuit board all of the way around until it became an open circuit, which in turn dismissed the fan motor from duty. There is a red circle in the second picture below where the damage was. Although I still don't know exactly what caused this I feel better knowing the problem part has now been replaced.





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The realization of this post must be credited to all of those who provided information regarding this identical problem in the following older posts...please forgive me if I have overlooked anyone.

http://www.mercurymarauder.net/forum...ad.php?t=47295
http://www.mercurymarauder.net/forum...ad.php?t=47975
http://www.mercurymarauder.net/forum...ad.php?t=43165

[Shora]

Thank you for taking the time to document the fix with such detail.

[Marauderjack]

Overheating of the transistor on the large heat sink is generally the problem??

"They" say you can R&R the transistor and apply some heat conducting compound and keep it from failing but when I removed mine it was such a PITA....I decided a new part was in order!!

Nice writeup and great photos!!

Marauderjack

[Spectragod]

Mmmm, bad solder joint, not enough solder or the use of low temp solder. Suck the solder joints out and re-solder with silver solder.

I would just repair and replace.

I have Snap-On socket sets with magnets in them.

I also have an extended warranty that keeps me out of things like this..

I approved this message.

[MM2004]

Excellent write up paying attention to detail.



Mike.

[Seneca]

My marauder must have had slightly longer heater hoses, It was in and out in about 15 minutes..interesting.. very nice writeup..
Seneca

Thank you to everyone who has contributed on the Blower Control Module subject. ixlr8 and thePunisher, thank you for all of the details! The job is a pain, but it is nice to have the HVAC working in the wife's car!

Has anyone repaired the module itself? I put the old one on the shelf just in case I have time to go through it.

Thanks again!

[SC Cheesehead]

Outstanding Post!

Another one to add to my notebook for futher reference.

[JimmyXR7]

Originally Posted by ixlr8

. . . The BAD BCM - what went wrong???

I smelled something burning before my fan stopped working so if this module was in fact the culprit of the problem I wanted to see some carnage. Once I removed the plastic cover from the unit I saw what I had previously "smelled". That was all of the validation I needed. When I turned the unit over I could see where one of the terminals had burned the circuit board all of the way around until it became an open circuit, which in turn dismissed the fan motor from duty. . . Although I still don't know exactly what caused this I feel better knowing the problem part has now been replaced.

I exited the freeway onto the streets on the way to work on Monday and my heater was on low fan. As I approached work I smelled something burning. That afternoon I noticed the fan for the vent and A/C would not run. I did a search and found this thread. I could not get the fan to work after repeated trys on tuesday and wednesday, so I purchased a replacement. Thursday afternoon I was in stop and go traffic because of multiple freeway accidents. The windows were down and the vent was on cold to try to cool off. After 15-20 minutes of this, all of the sudden the fan started to blow.

I did not touch any controls and it started to work by itself. It has been working since on medium and high fan speeds. I have not tried low fan speed.

Has anyone else had this problem?
Why put in another control module if something else is the problem.

Jim

[BAD MERC]

Excellent write-up!!! It is poignant stuff like this that makes maintenance easier for those that know little about newer cars. In hindsight, I SHOULD HAVE written up the blend door replacement recently executed on mine by his majesty - Carfixer.

[ixlr8]

Thanks for all of the compliments here - I have used this forum so much to look up information I was glad to be able to contribute something!

[RF Overlord]

Thank you, ixlr8. It's this kind of thing that makes this site so great!

I agree w/Spectragod...bad solder joint. Don't throw the old module away. Fix it or have a friend who can solder fix it.

[hdirish50]

Thanks for posting this thread. I recently replaced the blower control module in my 03 MM and your instructions (with photos) helped me out a lot.

[houndsman07]

+1 to what hdirish50 said. He posted while I was reviewing your instructions in prep to replace mine this afternoon. v/r mark

[Black Machine]

Thanks for the in depth description of how to replace that part. My fan quite blowing about three weeks ago and the only time I can get hot air flowing is @ highway speeds. I have been putting the install off for weeks but the recent east coast deep freeze has motivated me. Thanks again.