E240 Flat Battery

[George Millar]

I have a W210 (E 240) March 2001.

I have found the battery flat after no past record of defect.Battery performance has been sound.

However without the ignition live, I have found the electrical blower running continously at a constant speed and I cannot shut it down.Consequently the battery cannot be charged sufficient for a starter start with the battery charger on normal output.It would appear that the battery is flat due to the air conditioning blower running on.

The air condition has been set up for summer running but the blower still runs with the ignition off.I have switched on the ignition circuits as there is sufficient voltage to power up the alarm facia.("No malfunction" is displayed) but the fault remains.

I propose to disconnect the battery and charge it separately, then reconnect it and carry out a start hoping that the air conditioning blower control circuit will reset itself to normal when it is subject to normal battery voltage.

Has anyone experienced this type of fault before and what was the remedial action required.

 

[Aussie Nick]

I am not sure about the e class but on the W202 c class it is possible for a defect in the blower fan regulator to cause this problem. I do stress that I refer to the C class and not the E.
Someone else may provide further or better assistance.

 

[jberks]

Spot on Nick - its the regulator on the E class too.
Above the passenger footwell, remove the kick panel and look up behind the dash. You will see the bottom of the fan housing. Going into it you will see a rectangular plug with 3 wires going into it. This plugs directly into the regulator. Pull the plug down. This will isolate the regulator, stopping power to the fan which will stop your battery drain.
You then need to check the power to the plug. With the ignition off, one wire should be live (constant - unswitched +12v), another earth and the 3rd (switch control wire 0-8v ish) should be dead. Assuming so, then the regulator is shot and needs replacing. If the 0-8v wire is live, then you have a switching problem.

 

[George Millar]

Thank you both for your help.Will carry out what you suggest and report the outcome.

Many thanks

George Millar

 

[television]

145 in the link sir

http://www.detali.ru/cat/oem_mb2.as...623716.634&CT=F&cat=65S&SID=83&SGR=045&SGN=01

 

[George Millar]

Thanks for the technical information.Problem resolved.It was the regulator.

Unit price £140 plus VAT

 

[television]

Thanks for posting back its always nice to know the result