Faulty blower motor AC CLK W208

[MB Noggie]

I noticed the battery was getting weaker and one day it was flat. I tried to charge it, but it was gone. Bought a new Bosch 100 Ah same as the one I had. The man in the shop was surprised because my old battery was looking quite new, but he tested it and it was not recoverable.

I put in the new battery, but already the first day in the late evening it was totally flat. So I must had a battery drain. My new small handy Ctek battery charger could not charge it, so I charged it with an old charger and it peaked.

So I went over the fuses and fuse 25 (30A) cut the sound of a blowing fan and the charging current was cut in half. So the "blower motor AC" seems to be the culprit.
It is now charging, but still needs some hours to be able to start.

I changed the compressor on the AC in the spring, it has been OK since.

So anybody had the same or have any clues?
Will I have any heating at all with this fuse removed?

It is winter here in Norway .. Brrrr... ;-)

 

[MB Noggie]

I have used the car now and it is no heating. It is the fan for the heating system that empties the battery. It seems to run even when ignition is off.
The battery is 100 Ah and it emptied it in less than 12 hours, it has a 30 A fuse. To me 8A seems to be high to run a fan in the heating system, perhaps it is correct?
By the way the car has the automatic AC with two displays. The car is a CLK W208 1999 230K The fuse is no. 25.

Any ideas?
Is it hard to change?
What needs to be changed?
What could be the fault?

 

[MB Noggie]

Does anybody have a wiring diagram over the heating automation and fan?

It seems that the display is working, but it seems to me that it isnt controlling the blower/fan speed. The fan doesn't stop after the ignition is turned off.

So any links to wiring diagram for control unit, display and the blower(s)/fan(s)?

 

[flango]

Its likely to be the resistor pack at the side of the fan when this fails it can cause the issues you describe. Its under the passenger side dash 10 minute job to changeI

 

[stephen coy]

As already explained, sounds like the control module/resister pack attached to the fan motor.

I had same problem, which was due to water from the a/c not draining away/damaging the module. I replaced mine, also unblocking the drain pipe found L/H side corner of bulkhead and wing under the bonnet. Also as recommended by MB member, I cleaned the pollen filter which is housed in a long narrow housing alongside the heater fan. (if your car is L/H drive perhaps the above is R/H side?)

 

[MB Noggie]

Thanks flango! Sounds great and a big relief
I have a friend who understands everything electrical/electronical who will hopefully help me.

I will check under the dashboard. Is it easy to get to?
Do I have to remove the dashboard?
Shall I buy a MB part or do I get the resistors or resistor pack via an electronics store?

By the way I love your signature slogan

 

[MB Noggie]

Thanks Stephen! Much appreciated

The compressor was changed in the spring, so have they been sloppy or is this no connection to the job?
And the unit is on the R/H side under my bonnet close to the firewall. as you indicate.

 

[stephen coy]

To access the fan motor just remove the panel above the passenger footwell. As advised, will only take a couple of minutes with a phillips screwdriver.

Eurocarparts supplied mine and recognised what I described I needed from my phone call to them. For peace of mind I took mine with me to compare with their's. Proved very straightforward in the end !