3rd row blower / vents not coming on

[Chrispy]

Hi all,

In the saga of diagnosing why my front dash vents won't come on at all (defrost / windscreen only) I've noticed that the 3rd row vents won't come on either.  Press the little button and the LED doesn't light up - nothing happens.   

I'm on a blown fuse mission anyway (which helped me figure out why my power outlet in the boot doesn't work ) but struggling with these other issues.

Spotted I'm missing fuse 126 from the boot fuse box but having borrowed another 5A fuse to pop in there temporarily whilst I buy some more of the little fuses, it's made no difference.

Anyone else had this?

Ta,

Chris.

[Pat Mustard]

https://www.google.com/url?sa=t&source= ... aEJrNIFDPA

[Chrispy]

This was an interesting read....

https://testing-public.carmd.com/Tsb/Do ... %2004%2015

About how ISTA cannot diagnose the 3rd row control unit .  Tempted to pull it apart and see if it's getting a 12v supply.  Could be the microswitch that's faulty, as simple as that.

Actually recommends a full power cycle on the car so I think a battery pull might be in order.

[Ducklakeview]

I had no problem communicating with/activating the rear blower using ISTA. I am however, using a genuine ICOM interface purchased from BMW, rather than one of the Chinese clones. May they can't do it?

Mike

[Chrispy]

I had it in for a diagnostic.  The control unit for the 3rd row is dead - totally non responsive so there's a fault code logged with the main IHKA unit.  There's power to it and connectivity is good but the unit is dead, so that's on order for replacement and coding on the 9th of July. 

Fingers crossed that sorts it - was going to post up in here after the event.

[Chrispy]

UPDATE: After taking it in to have the 3rd row control unit replaced, it didn't fix anything.  They had another X5 in the yard that was being scrapped so they borrowed the main IHKA unit from it (the one from the dash with the buttons on) and plugged that in (no coding at this stage).  As a result the 3rd row climate fired into life and the direction of the air was once again controllable in the front.  Obviously minus coding meant that the display on the dash didn't work and etc but it was enough to prove the point.  A faulty main IHKA unit.

Looking at the parts catalog, the failed unit had been superseded by a new one with a different part code.  Old part code - £500 ish plus VAT.  New part code, £850 plus VAT.....sigh.

So I managed to find a used one on eBay for £110 so waiting for that to be delivered and then see how we go.

[Chrispy]

Update No.2:

Fitted the replacement part myself last night (pop out the front centre air vents with the glove box open, 2x screws to remove at the top of the main panel under there, then pull out the fascia to reveal the cabling behind the IHKA and CD player unit).  5 minutes later it was all cabled back up and hey presto we have fully functional front vents again including the iDrive integration where it shoes where the direction of the air is going etc - no coding required for this.

However the 3rd row is still dead but I was warned without coding this would be the case as the replacement unit likely isn't from a 7 seater and won't be aware of its existence in mine, so I've fixed one (big) issue quite easily and the other just needs coding to sort.  I know coding will sort this as a borrowed IHKA unit from an older 7 seater brought the 3rd row fans up straight away but didn't communicate with the iDrive properly as the main screen air direction stuff didn't behave itself.  Booked in for coding on the 10th of August.