One side heating ?
 

With the cold snap today we had the heating on in the 2006 XC90. But only the drivers side was blowing warmer air - the passenger side was blowing cold air.

All switches etc were lit and working as expected to blow warm - but no warm air for the passenger :-(

Any suggestions where to look first? Would a code read help ?

Thanks for any input - John

Hello John.

I would say yes to codes, must be through Vida or a car specific reader though, generic readers won't find the climate control units.

I don't know specifically for the XC90 however on the V70 P2 which is a very close relation, it's usually a problem with stuck flaps on the climate unit that can be motor or position sensor failure.

Put money on it being the AQS sensor in the scuttle air intake. Exactly the symptoms I had, about £95 from Volvo.
PIA to get to it as the wiper arms and the scuttle needs to be removed, then a bit of contortion where you really cant see what you are doing to twist to remove the sensor.

Once replaced heating was back to normal.

I would have thought the AQS would have thrown a fault code but may be wrong.

Hope it helps :regular_smile:

Found a YT video on replacing the AQS - does look fiddly - albeit straigtforward. Might be good to get a code read to see if it could be something else.

How easy is removing the scuttle to get at it - I have never done that ?

Scuttle is easy, the PIA is the wiper arms ... you really need a puller.

The AQS removal, I ended up getting my daughter with small hands rather than my shovels to twist it out.

Further digging finds the thread below - where Clan and others state....

"The AQS will not be the cause but likely to be i wouldn't know about that , but his first problem with blowing too cold one side has nothing to do with the AQS just about all the cars fitted with them over 8 years old have the AQS failed fault code and contunue to work properly . The fault is probably a faulty driver's side air temperature flap motor"

Any thoughts on that chaps?

https://www.volvoforums.org.uk/showthread.php?t=246271

Can only advise that in my case after the AQS was replaced in mine, the hot air was restored, even tried unplugging it and cleaning the terminals and dusting the sensor before replacement to no avail.

I'd try and get the codes read, as I was advised by my dealer that the AQS being faulty can bring the bus down that controls the heater flaps etc.

OH!, and the passenger heat would not heat, after replacing the unit, again normal function restored.

Thanks will try and get the codes read and may just take a punt.

Do you know the Volvo part number you got ? And what MY and engine do you have?

Though I suspect there may be more than one and it would be good to know which one to get for my April 2006 XC90 2.5 T SE.

Cheers

EDIT: Just noticed that you are selling lots of spares after selling the beast - and it looks to be a later model and diesel than mine

Mine was a MY09, and the 185BHP 5 cylinder lump (gosh I miss that car!.) I will post the part number when I get home as the box and the old one are in the garage.

FRF can advise ... they supplied mine.

AQS for my 2009MY was 31348901, cost was £79.63 + vat

Got it from FRF using the C3 code for the forums discount.

Best check, but I would think/guess all the post facelift cars use the same sensor.

Correction, dont know how I wrote that part number down, it was on the invoice in ink in my writing :speechless-smiley-5 ... prob me I think why I dont know ....

The correct info is

The old part - 31250722

The part FRF supplied to replace it was - 31418053 and the box description was Givare .... sensor?

Sorry about that.:confused:

Cheers - waiting on a reply from FRF re price and availability.

Pretty sure it is this now as I just checked and the passenger heated seat is not working either and the switch lights are on.

The cheapest way to check is to unplug the AQS.
If heating returns to normal, it was the AQS.
You don't need to buy and fit a new AQS to diagnose.

Thanks cheshired5, good idea. I will give it a go.... once I can find some scuttle clips (see my other thread).

If the heating returns to normal, are there any major downsides to just leaving it disconnected?

Cheers John

You just don't have AQS so if you're in a smokey/polluting traffic environment, you'll need to manually recirculate the air with the button on the climate unit then press again to return to fresh air intake when ready rather than it being done automatically.

AQS does not have anything to do with heating system BUT, an internal fault may/will cause the LIN bus to go down which WILL affect pax side heating and seat heater.

Thanks again Greg, that's what I am going to test, as soon as I can find the scuttle clips :-)

I concur, exactly what happened to me, AQS replaced and all back to normal.:regular_smile:

Good call fellahs! Got the job done today, disconnecting the AQS was surprisingly easy after I eventually got the wiper arms off.

All heating restored to the passenger side - happy Mrs Brennand :-)

I may replace it if I can get a cheap one from a breaker - but not worth it for the £250 the main dealer quoted.

For reference the AQS volvo part number on my model is shown below.

Buy the Hella brand - it is the same, eg.

https://www.autodoc.co.uk/car-parts/oem/30676508

Wow, was that to do the work as well as supply the part? ... last year from FRF it was only £79.63 + vat for the part.

See this thread

https://www.volvoforums.org.uk/showt...=246271&page=2

:eek: That's daylight robbery, I got mine last September/October from FRF and as I said it was £79.63 + vat for the part inc the forums C3 discount, brand new in a heat sealed anti-static bag in a Volvo blue box, delivered within 2 days.

I think you did very well!

a quick google looks like £110 or if you go with a US part supplier $95'ish

Wonder why they are so expensive ... I went with FRF, but even my local dealer was only wanting £115.

My quote was from my local Volvo dealer - FRF never called me back! Only thing I can think of is that yours was off a newer/different model and may be more plentiful and readily available - but even so.... I was as they say... gobsmacked.

I wont go for a third party one as reports in this forum say quite a lot of them "fail" or dont actually fix the issue

Well that's a thought, but Id guess they are all more or less the same, save any revisions ... mine was a 2009MY D5 SELux but maybe that would explain the cost difference, a bit galling though.

Definitely the AQS, mine was like that when I purchased it, heat only on the drivers side and no passenger seat heater (although the led’s on the dash pretended it was working) I removed the aqs altogether just to be sure, heaters now work correctly as does the passenger seat heater. I managed to remove it without taking the wipers off, I wouldn’t recommend it though as the plastic panel looks like I took it close to it’s stress limit

Update : whilst the initial thought was that all is well, the heater controls are not: the heat goes from hot to cold every five seconds, with the fan in the lowest setting you can hear the flaps turning round and round.