W203 Dome Light Fan Not switching off

[CrazeUK]

Hi Guys.
I have a C220 CDI W203 Auto.

Recently after the installation of a aftermarket car stereo i have found my battery keeps dying.
Logically we can assume its the stereo, but thats for a different thread.

I have noticed that i keep hearing a whiring sound from the dime lights. I have had it since i bought the car used but never thought anything of it until the battery issue.

So today i sat in the car, locked it and sat for 30 mins.
The fan didnt swutch off at all.

How much of an issue is this?
Is there a fix?
Will this add towards the battery drain?

As always thanks in advance.

 

[markjay]

We are talking about a C-Class, 1999-2007, right?

And I am assuming you are referring to the lights cluster in the roof near the base of the rear-view mirror?

I have a (facelift) W203, and I don't think mine has a fan inside the dome lights cluster.

At any rate, I never heard any sound coming from that area.

Do you have a sunroof?

 

[lexman8]

Okay, different car, but mine has a small fan in the dome light cluster that's used to draw in air from the cabin and pass it over the interior temperature sensor. Obviously, it only runs with the climate system/ignition switched on and is very quiet.

There's also another temperature sensor with a similar fan in the lower dash on mine but the C Class may be totally different.

 

[CrazeUK]

Hi guys. Yes silly me.

I should have said it's a 2001.
I didn't know what the sound was so Googled around and everything seems to suggest their is.

As
Mentioned aapparently it is to draw air over a sensor.
also when I unclipped fitting their where additional wires to the lights and vents built in.

I also have the little one near the climate controls.

 

[KillerHERTZ]

That tiny fan would take weeks to drain the battery id imagine

 

[CrazeUK]

That tiny fan would take weeks to drain the battery id imagine

I would assume the same.
Although i think there are a number of other things that are probably draining the batt.

1. The battery is old, probably really old, but kwikfit did one of there diagnostics and said its 76% which is considered "good" (what ever that means).
2. I had a bluetooth adapter in the ODB2 port, which was on an always on state.
3. I noticed when i pulled the stereo out with the car off that thee was a green flashing LED inside it. Not sure what it signifies.

BUT having said all that that little fan is concerning / anoying now.

 

[lexman8]

That tiny fan would take weeks to drain the battery id imagine

Yes true, if it was just the fan, but it's controlled by the climate ECU/OCP so it looks like at least part of the climate system or the OCP isn't going to sleep. If so, the current drain will be higher.

But as the OP says, there could be other drains as well.
_

 

[CrazeUK]

Yes true, if it was just the fan, but it's controlled by the climate ECU/OCP so it looks like at least part of the climate system or the OCP isn't going to sleep. If so, the current drain will be higher.

But as the OP says, there could be other drains as well.
_

Okay so how do i get it to sleep normally?

 

[davidjpowell]

Okay so how do i get it to sleep normally?

According to my wife you start talking about Le Mans.....

I'll get my coat:fail

 

[CrazeUK]

According to my wife you start talking about Le Mans.....

I'll get my coat:fail

Lol.
I was thinking about stroking it to sleep.
lol

Seriously though, its concerning me. It never came up in my Snap On scan not so long ago.

ALTHOUGH i did notice most of the issues where on the passenger side.
Pasenger squib
Lock mechanism
Low voltages etc.

 

[lexman8]

A low system voltage can cause false error messages to appear in some of the car's systems. Diagnostics are best done with a fully charged battery. Most plug-in readers can only access (at best) some of the car's systems so not all faults will appear.

Regarding the sleep issue, and assuming your car doesn't have a two battery set-up, you could try forcing a reset of the various ECUs by disconnecting the battery for at least 10 mins. However, after doing this you will need to sync the windows and sunroof again.

You might also want to check for any signs of dampness in the passenger side footwell and ensure that the heater air intake's water drain isn't blocked.

If the above doesn't work, it'll probably need a proper STAR diagnosis.