Help Needed - HVAC related

[Black_Noise]

Update: Replace the BCM, works fine now.
Thanks again guys




Not the Blower control module
Not the Blower motor

It started intermintanly not blowing, but I still have full control of if it comes out of defrost, floor, vents, a/c or no.

When Im going above 40mph or so there is some small air flow, I can direct it wherever, and if I turn on the a/c it does get colder but, doesnt blow.


I removed the BCM today, inspected it, no burns, looks great.
I jumped the blower motor and it fired right off when it gets juice.


So what else could there be?

Anyone ran into this problem?


Could HVAC head unit be bad but still command A/C and change the position of air flow?

[Richy04]

The BCM is the problem, it may have failed electronically with no bad traces at all. If the blower works jumped out and the EATC and fuses check out, bet on the BCM being faulty. Richy

[Krytin]

The BCM is the problem, it may have failed electronically with no bad traces at all. If the blower works jumped out and the EATC and fuses check out, bet on the BCM being faulty. Richy
+1 - I've had the exact same symptoms that you describe in the first post on an 03 & 04 and both times it was the BCM. Try tapping the module when the blower isn't running when it should be.

[Black_Noise]

tried tapping it with vent on half blower speed, nothing happenes.

I think I will talk to the other MM guy in town and see if he will let me plug mine into his car, shouldnt be hard to just leave it my BCM hang in front of his plugged into his car, and see if it does or doesnt work.

Thanks guys, I was thinking it could only be the BCM or the head unit.


I will post up results whenever I get a chance to do this.

[Richy04]

Its prob not the EATC (head unit) the likely failure is the BCM, its about 60 bucks give or take from FLM. The BCM may be controlled by the EATC but the little wheel on the EATC will control it directly when in auto or manual air settings. Look at yours good around the large pins on the EATC, you may not see the cold solder joint but chances are if you follow my instructions, you can fix it. Its a pain to get out and in but just change it out and it should solve your problem..

You don't have to remove the hose, you can get a few bungy cords and use one to hold the hose out of the way and the other to hold the sensor mounted right above it. You will need a 1/4 inch ratchet set and something to hold the screws into the socket when you replace them. Also remove the coil cover so you can swing the coil harness out of the way, it gives you some more room to work.

Regards, Richy

[Richy04]

I tapped mine as well and it didnt work, once I reflowed the solder, it worked like gangbusters so tapping it may or may not work. If the unit failed or the traces burned enough, hitting with a Louieville slugger isnt going to get it to work again.

Once again, if anyone has EATC's,LCM's,BCM's, air compressors etc.. On their shelves I will repair them and keep em available for others who need them.

[Richy04]

It started intermintanly not blowing,
So what else could there be?




Your answer is in the question, intermittent means there is a bad trace or failing component on your BCM. When it heats up, it breaks contact causing the blower to stop, when it cools enough, it will reconnect and spin the blower. Look good at the large pins on the board..

[NOMARQUIS]

Is the BCM the part that is located on the right side of the firewall next to the blower motor?

[Black_Noise]

updated 1st post.

[Richy04]

Is the BCM the part that is located on the right side of the firewall next to the blower motor?

Yes, its right behind the passenger head with an orange sticker on it. See this thread for pics..

http://www.mercurymarauder.net/forums/showthread.php?t=55071

[Black_Noise]

Its kinda a PITA to get out, but its do-able without taking off the heater hose or cam cover.... like I heard a LONG time ago.

Its about a 45 minute job, for those of us with big hands

[Richy04]

I took out the coil cover, not the cam cover. My "meat hooks" made good use of the extra room. LOL

It gives you another two inches to play with..... Thats what she said... Beat you to it..!

[Black_Noise]

whatever works