Vent fan continues to run

Post by **Aznav** » 11 Jul 2019, 13:55

Lately I have noticed that the vent fan in my XC 90 will continue to run when I get out of the car. If I don't have my hearing aids in I will sometimes miss it running. It is not every time. In fact, maybe once a week or every other week. It does not shut off with obvious results. Any hints?

Post by **bmdubya1198** » 11 Jul 2019, 18:19

Somebody on Facebook just asked about the same thing yesterday, it's completely normal. It's an "after-blow" feature in P2 Volvos to defrost the AC system and prevent mildew buildup. It may run for about 30 minutes after shutting off the car.

Post by **Aznav** » 12 Jul 2019, 16:38

WHOA!! THANK YOU! WHO KNEW??

Post by **bmdubya1198** » 12 Jul 2019, 19:43

It's interesting, I've never noticed this before in either of my P2s.

Post by **ggleavitt** » 12 Jul 2019, 21:15

Aznar wrote:11 Jul 2019, 13:55
Lately I have noticed that the vent fan in my XC90 will continue to run when I get out of the car.

It does not shut off with obvious results.

I like the answer in the earlier post and it's my understanding that the afterblow software function was turned on by default with many of the early XC90s so it’s a possible scenario.

I had the function activated on both my vehicles (was deactivated when I took ownership), the '05 as part of the dealer's 7.5k "checkup" and with the '08 I paid to have the function activated. It was stupid expensive IIRC but I really like the feature and it's made a difference over the years to me, especially where I live.

See viewtopic.php?f=9&t=49926 , jimmy57 quotes the TN which shows the criteria a little lower down and adds a few details that may also be helpful in determining exactly what's going on. It's for another model but the function is more or less the same.

I believe some vehicles have it on by default and some do not. See- https://forums.swedespeed.com/showthr...le-on-XC90-V8s for one example specific to V8s where it’s maybe never turned on by default.

Which brings me to the first sentence in the OP's quote above. If the interior fan is running when you get out of the car, then that's not afterblow. And if you hear it only when you put in your hearing aids, I'm wondering if it might be the little interior cooling fan behind the 3-slot grate mid-right on your climate panel as jimmy57 describes in the post, something to consider. The climate fan on afterblow is pretty loud when you hear it, but you should only hear it a little less than an hour after stopping the vehicle. I heard mine in the garage the other day, ran pretty much half speed for the 15 minutes the TN calls out (full speed 7 minutes for '03-04 I think), and a little more than an hour after I shut it down. That's afterblow, at least as I’ve ever known it.

And if I interpret the second sentence as meaning the battery goes dead, then it seems like you might have another issue or more than one issue at play. Is this correct, the battery goes dead?

Battery original by any chance? Any other functional module on the car not working consistently?

One thing to consider if you’re not the original owner- If the battery has been changed, capacity for a T6 should ideally be the Group 49 battery versus the smaller Group 48 that's in many of the 5 cylinders, although it can vary depending on what accessories came with the model I think..

Regardless of engine type, both vehicles can take the larger 49 battery by moving the bracket at the bottom right or the battery tray (I replaced the original Volvo ’08 Group49 lead acid with a Bosch AGM, and moved it into the ’05 couple years ago. That car loves it).
If you do find yourself needing a new battery and the charging system is sound, get the large capacity one.

If you could clarify the above, might help to get closer to the cause. Something tells me this may not be afterblow.

Good luck.
edit 071219- fix typo

Post by **bmdubya1198** » 13 Jul 2019, 08:53

That's true, the after blow shouldn't come on until about 30-45 minutes after shutting the car off. If it continues to run after removing the key, your blower resistor may be bad. This part here: https://www.fcpeuro.com/products/volvo- ... wE#fitment

Post by **oragex** » 13 Jul 2019, 10:07

Maybe try to see if it spins like thins only when the A/C is used. And also for how long it spins. May get back to the car 1h later see if it's still running.