Heater fan not switching off

[s4rap]

Hi all, strange one this. Just got back from longish run in the clk and the heater fan won't turn off. It is still running when the display is saying off on both sides,it still runs when the ignition is turned off and still blows when I take the keys out of the ignition.Any information please chaps. Easy temporary fix was to take the fuse out! Sorry car is a 2001 clk430. Thanks.

 

[gbjeppm]

Hi all, strange one this. Just got back from longish run in the clk and the heater fan won't turn off. It is still running when the display is saying off on both sides,it still runs when the ignition is turned off and still blows when I take the keys out of the ignition.Any information please chaps. Easy temporary fix was to take the fuse out! Sorry car is a 2001 clk430. Thanks.

If I remember correctly your car has the REST function, is the REST light on? REST uses the residual heat from the engine to keep the car warm after the engine has been switched off.

Although I thought it stopped with ignition off.

Anyway if the REST light is on, press the button, and it should switch off.

If its not that, there is a reset procedure you could try.

 

[s4rap]

I've never noticed a rest button. What's the reset procedure thanks.

 

[gbjeppm]

Here you go, assuming you have the digital climate in your W208.

If yours looks like the unit in the video, you do have the REST function.

https://youtu.be/aNrlQ-rCJjw

 

[s4rap]

Ok thanks, never noticed the rest button before. I'll Have a fiddle with it later and let you know how I get on. Thanks for the link!!

 

[Diesel Benz]

If you did not press the REST button, then the heater fan regulator has likely failed.

 

[s4rap]

Gone through the reset and it's no different . The only way I can turn the fan off is by removing the fuse.

 

[Jacasino]

Have a 2016 W447 we’ve had a few warm days and I keep finding the fan has switched itself back on when I return to the van, seems bizarre.

 

[mersum1es]

newer cars has been problematic fan design where moisture cause fan engaging when car locked, search threads I posted the bulletin somewhere

 

[NickVito]

Re the W447 ... it has a feature... when you unlock it on a warm day, the fan comes on for a while presumably to start to ventilate the cabin. I don't think it can be disabled... I checked with the dealer.

 

[Jacasino]

Re the W447 ... it has a feature... when you unlock it on a warm day, the fan comes on for a while presumably to start to ventilate the cabin. I don't think it can be disabled... I checked with the dealer.

I did wonder about that, many thanks for the answer, that’s a relief.