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Discussion Starter · #1 ·
I Have only had my one-year old V40 Cross Country for about seven weeks. This evening for the first time, when I switched off, a fan (air conditioning fan?) switched on and continued to run very loudly for several minutes. Shouldn't be the engine cooling system fan as we had been on a short evening run at very moderate speed, with cool ambient temperature. Is this a normal automatic function (possibly to ensure dehumidication of the cabin air and AC system as I noticed the windscreen had been misting up a little) I cannot find any mention of any such function in the handbook though. Can anyone throw any light on this please?
 

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I had this 80 miles into my brand new V40. I'm pretty sure it is due to the engine doing a DPF regen.

The following is my understanding of this (may not the 100% accurate). In order for the DPF to be cleaned, the exhaust (and thus the engine) needs to run really hot. As such, if you stop the car when it is doing a regen, the fan stays on to cool it back down. The reason for this is on turbo cars, if you turn off when very hot, the residual heat in the turbo can over cook the oil. Oil that gets too hot can leave deposits which causes wear - in turbo this can attack the oil seals. The fan tries to get temps back down quickly to minimise the max temperature the oil sees.

During a DPF regen, you may also notice that stop start does not operate. This is because it needs to keep things hot for it to work.

More info on DFP regen in general at the link below:
http://en.wikipedia.org/wiki/Diesel_particulate_filter#Regeneration
 

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Discussion Starter · #3 ·
Hi MJW45 - thanks for that very clear and logical explanation. The stop/start was indeed not working so I am pretty sure you are right. It's a pity that Volvo in their wisdom have dispensed with the engine temperature gauge (and also that that they didn't give it a passing mention in the owner's manual) . Once again I phoned my Volvo dealer and the guy I spoke to did not know about this!! He couldn't believe that my previous petrol-engined C30 didn't do it also. To a Volvo employee this should not be "rocket science" it's time they sent some of their staff on product familiarisation courses.
 

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Hi MJW45 - thanks for that very clear and logical explanation. The stop/start was indeed not working so I am pretty sure you are right. It's a pity that Volvo in their wisdom have dispensed with the engine temperature gauge (and also that that they didn't give it a passing mention in the owner's manual) . Once again I phoned my Volvo dealer and the guy I spoke to did not know about this!! He couldn't believe that my previous petrol-engined C30 didn't do it also. To a Volvo employee this should not be "rocket science" it's time they sent some of their staff on product familiarisation courses.
If you turn your display to performance mode (if you have the TFT screen), then you can see the engine temp.
 
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Discussion Starter · #5 ·
That would have been nice but I have the conventional instruments. Thanks anyway. I wonder why there couldn't have been a light or other indication of active regeneration taking place apart from the more subtle indications such as loss of efficiency which for me at least are not so easy to spot.
 

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This came up on the forum last year. Scared the pants off me when my 2 week old car was running on after I got out and locked up, was still going when I got back to car 10 mins later. Has only happened once since. If I remember correctly it is part of the cleaning process and somebody had this confirmed at their Volvo dealer.
 
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