RobPF

Hi,

I'm desperately trying to find out via some good advice or wiring diagram how to disconnect the A/C fan in the overhead console?

Its causing a power drain and I've already taken the fuse out and disconnected it's power supply, the only problem is that when you do this you lose other things i.e. lights etc. etc.

I want to snip the wire for the fan if possible but have no idea which wire it is through.

Any help?

Thanks,

Rob

Crna Mechka

Wondering if Rob ever got to the bottom of this as I'm experiencing a similar problem. I'll be replacing the voltage regulator over the weekend but have a feeling it won't be the complete solution.

So here's my story:

Ever since the winter started here in the northeast, my battery's been kind of acting up. At first it was rough starts, seat controls not working at times, and problems closing the sunroof (the sunroof issue only came up after the battery died on me a few times).

Recently, things have gotten worse as the battery began draining overnight leading me to have to re-charge it every morning. So after some research, I found out our seat control modules can go bad and continue drawing current even after shutoff. So I decided to unplug them (both driver and passenger side) and re-charge the battery once again to see if they are in fact causing the drainage. I've come to find out the answer is no as the battery still continues to drain even after unplugging the seat control modules.

It's actually incredible the pace at which the battery drains after a FULL recharge. For example, after a full charge and going into dynomode to check realtime voltage of battery, it reads 13.0V. Great, well, after disconnecting the charger and just sitting in the car with everything off...the voltage drops an increment of 0.1v/5 seconds.

Basically, as soon as I disconnect the charger, the battery instantly drains within a minute or two.

Next thing I will try is pulling the fuses for the dome lights.

If anyone has any more information on this please share.

P.S: I tried the 1cm x 1cm paper trick on the overhead console fan (which I assume is the black slotted circular piece of plastic between the rearview mirror and domelights?) and no suction is present...car on or car off...there is no air moving through that thing.

Crna Mechka

I'll continue posting any updates I find here.

So as I was browsing through the Wiki section, I found this line (not an active hyperlink) under Common Problems: "Flat Battery due to front seat modules or aircon sniffer fan in the overhead console not going to sleep."

...but I don't see a Wiki link leading to the DIY/solution.

Did the webmaster forget to include a link?

Crna Mechka

Is it possible that a bad battery would not hold a charge? Thing is the charger is always able to fill it to 100% capacity which prompts the green "Charged" light to come on as well. I figured if the battery was bad the charger would spit out an error (yes it has that capability).

Let me also add that I've searched this entire forum as well as BW with little results (it's not the seat control modules, nor does the overhead fan ever come on. I've even pulled the fuses for the domelights).

I'll be hooking her up to a STAR diagnostic system later today...hopefully I'm able to narrow down the problem that way.

DACHIGGA

If you have electric seats. look under the seat and disconnect the seat module power and see if you still have a battery drain. Should be the big connector with the thicker wires.

If you no longer have battery issues, it's the module. It's a common problem that can be "fixed" with a couple or relays.

SunnyRayToronto

Check the date code stamped on the negative terminal of your battery. Car battery should be replaced every 5 years,... replace with OEM Mercedes-Benz car battery.

Here's an interesting link posted from Alswag, a fellow Canuck-le-head, on BenzWorld,.... a how to DIY on finding parasitic electrical draws
http://www.benzworld.org/forums/w203...y-morning.html

Crna Mechka

Already tried the seat control module fix. Still she continues to drain. I also pulled the fuses for dome lights and same result except the drain is a bit slower this time...leads me to think it could be the battery.

Crna Mechka

I have the battery exposed right now.

Read that too fast. I checked the neg terminal but dont see any numbers on it?

edgarinho10

If anything, it sounds like a bad battery. When is the last time you replaced it? Or better yet how long have you had the car?

Crna Mechka

Here's a snapshot

https://www.dropbox.com/s/kmez8lhwys...2017.21.07.jpg

edgarinho10

You should have a circular colored sticker with 2 digits then a slash followed by another 2 digits

One of my batteries reads "05/10" basically meaning it was received by the Mercedes dealership on May 2010 and installed somewhere within a 3 month time frame following that date.

Crna Mechka

No sticker here. The battery is probably due though so I'll take that as the next step.

Anyone know of a reliable vendor of genuine MB batteries in/around the Boston area?

Oh yeah...so I ended up diagnosing with STAR and got a plethora of faults all linked to the electrical system. Not gonna jump to conclusions though they'll probably clear after a new battery.

edgarinho10

Dealership is your best and only bet. If you don't think you can successfully replace the battery yourself, shed the couple extra bucks for the labor. It will give you peace of mind.

Crna Mechka

Yeah doesn't look like I have any other options really. They want a little over $100 for labor to replace it..think I'll do that myself for a bit cheaper.

Thanks for all of your replies, much appreciated.

I'll post back when the new battery is in

SunnyRayToronto

If you install yourself,... follow instruction to disconnect and install car battery in your owners manual.

Call MB-USA roadside assistance,.... they charge the same for OEM Mercedes car battery as MB dealership,..... they'll come to you,.... they now charge a small service fee (used to be free) to install the car battery (maybe $25 but not sure,... definitely less than $100),....

Crna Mechka

Ended up getting the battery at the stealership. Came out to just under $150 with a $50 off coupon (big shout to MB for that).

So out with the old in with the new and voila! She fires up no problems..didn't even have to resync anything!

Thanks again guys, another problem solved

edgarinho10

That's not bad!

How much was the battery itself?

Crna Mechka

They quoted the battery around $190 (with core charge) so after returning the old battery it came out to $130 and some change (with that coupon).

Also ended up replacing the alternator pulley and voltage regulator yesterday, along with elevating starter fuse from 15 to 20 amp.

She's a healthy girl now

tschureman

I am having battery drain issue related to fan constantly running in overhead console. Has anybody come up with a solution or a way to disconnect the fan?