e320 cdi heater fan runs with ignition off .

[ramsanjan]

i have a 2000 e320 cdi .
last night after driving the car when it was switched off the fan would not stop . even though the car was locked the fan ran at full speed all night until the battery was flat .
today i jump started the car and i still could not switch the fan off .
i tried pulling out fuses to no avail , in the end i unpluged the fan above the passengers feet .
what's wrong with it ? any ideas ?

 

[Xtractorfan]

I would have thot that the ignition would have killed the power supply ..my thinking is a heater control solenoid has stuck and kept the circuit live, this is why the fuses didnt cut the power as they only control the lesser feed to energise the solenoid, i would check the solenoids and see if one is sticking closed.

 

[hmang]

how about the rest button ?

 

[panason1c]

I would go for the fan control unit gone bad, this unit is always live, even with the car locked, as it controls the 'rest' function which allows the fan to continue to run at anytime, when selected.

The fcu is usually located alongside the fan and is probably where you pulled the plug from.

 

[panason1c]

how about the rest button ?

The 'rest' feature is designed so that when the battery drops below a pre-determined voltage the 'rest' function is switched off and disabled so as not to leave you stranded with a flat battery.

 

[television]

Your car must be a 210226 and there is nothing listed for this fault

 

[jberks]

I'm with Panasonic. The plug that you pulled goes to the regulator. This is pretty much the only thing that can do this, and they're known for doing this. The test is easy enough.

With the ignition off so the fan shouldn't be running, check the 3 pins on the plug you removed. Only one should be a constant live and the other is the switch signal. The 3rd is -ve.
If the switch signal is dead (test by switching the fan on - you should see 0-7v roughly depending on switch position), then the regulator is shot. £125 from the dealer when I changed mine 3-4 years ago .
If you have power to 2 pins with everything switched off, then you've got a switching fault.

 

[ramsanjan]

thanks guys i will try your sugestions at the weekend and let you know the outcome .

 

[ramsanjan]

i tested it on the weekend and everything was ok so i got a new regulator and fitted it .
everthing is ok now . thanks .