When we put the blower on full for de-misting we get a noise coming from above the headlining in near side rear cabin. As far as I can tell it's above the pillar with the air bag, so if you are sitting on the left hand rear seat it's above your head and to the left. We have the velux roof if that makes any difference? I've held my hand against the headlining and I can feel a small vibration when the noise starts. It's a kind of slight clunking noise and I have absolutely no idea what the connection is between the blower being on in the front of the car and the rear passenger headlining.

Anyone have any ideas?

When we put the blower on full for de-misting we get a noise coming from above the headlining in near side rear cabin. As far as I can tell it's above the pillar with the air bag, so if you are sitting on the left hand rear seat it's above your head and to the left. We have the velux roof if that makes any difference? I've held my hand against the headlining and I can feel a small vibration when the noise starts. It's a kind of slight clunking noise and I have absolutely no idea what the connection is between the blower being on in the front of the car and the rear passenger headlining.

Anyone have any ideas?

Just a guess but what comes in must go out. The outlet vents must be somewhere - perhaps in the rear of car and perhaps a flap on one of these vents is vibrating - just intuition - haven't been out to look !!

Just a guess but what comes in must go out. The outlet vents must be somewhere - perhaps in the rear of car and perhaps a flap on one of these vents is vibrating - just intuition - haven't been out to look !!

Have been googling and found this post on a Jaguar XJ40 forum which sounds very similar...

Think i have traced the problem to something loose behind the headlining,sounds strange i know...but when i first heard it,i swore it was coming from above...also only appears when the heater fan is on max..and today i opened the sunroof slightly and the rattle stopped...closed roof and it was back???

Hmmm...don`t fancy taking headlining down though...what a dilema...

With This reply that suggests an issue with the outlet vents as well...

You are not imagining things , i have seen on my just washed car , small bubbles emanating from the sunroof seal when i had the heater on full whilst i was drying off the car , the air from the cabin exits through the boot via the side vents behind the side of the bumper , my theory is sometimes the air cannot escape quickly enough through the boot and a little excess pressure builds up and the sunroof seal is not air tight so some exits there .

In your case there may be a piece of cloth loose in the panel which is flapping about in the breeze , i would think this noise would go if you had a window open a little , the amount of times you put the fans on full is not often and i wouldn't worry about it

However I am obviously worried about this on a two day old car. Can anyone else with a velux roof try putting the windscreen de-mist blower on full and see if they can hear anything similar?

If you open the rear doors you will notice there is a small outlet duct half way down the curved bit. That must be dragging air from somewhere. I wonder where?

If you open the rear doors you will notice there is a small outlet duct half way down the curved bit. That must be dragging air from somewhere. I wonder where?

Cheers, I'll take a look at that. I'm taking it into the dealers tomorrow and we'll see what they say about it.

No been on the site for a while and reading through some of the threads it seems to have kicked off a bit! So hopefully we still have some users on here to respond to my update

I've never have got round to taking the car into the dealers about the clunking noise when the blower is on as it's mostly the wife that drives the car. However I was using the car the other day and heard the noise again. I jumped into the back seat to see if I could locate a noise. It seems that when a door is open the noise disappears and when I shut the door I could hear it louder. I traced the noise to behind the top of the rear offside wheel arch. This must be sending vibrations up into the cabin/headlining etc. So am calling my dealer today to book it in for investigating.

Sounds like the valve in the rear of the car to let the excess air out? When the fan is running and pulling fresh air into the car it has to go somehwere, there is some sort of no return valve hidden to the rear of the car.

Sounds like the valve in the rear of the car to let the excess air out? When the fan is running and pulling fresh air into the car it has to go somehwere, there is some sort of no return valve hidden to the rear of the car.

I'll mention that when I give them a call. Nice one, thanks.