Cold air only+heated seat u/s passenger side.
 

For the past few weeks my car, XC90, 2004, 51000miles which I have owned for nearly seven years, has only blown cold air out of the passenger side, drivers side is ok. And the heated seat has refused to work passenger side as well.
I have been trying to get to the bottom of the fault without resorting to main dealer help, primarily I'm being tight, the car is really getting too old to be paying £100 an hour labour.
There was power getting to the seat, but none coming out, I'd read on this and other Volvo forums that similar faults had been cured by replacing the seat module, I tried this, didn't work.
I also took the glove box out, and by moving the heater control arms manually that are attached to the stepper motor I could get hot air to come out of the passenger side, further investigation showed that the stepper motor wasn't even trying to move, so I thought I had found the cause of the no heat problem. Replaced the stepper motor, guess what? Still not working, Doh!
I should also mention that the only fault codes showing on my PPC reader were for the headlamp washer relay which I had taken out years ago, didn't like them squirting unnecessarily on a clean car. Then yesterday a fault code came up that hadn't before CCM DD00 Lin Bus1, and also CCM 0040 air quality sensor, I don't have VIDA, to be honest I'm not very good with laptops etc, I doubt I could work it.
I was lay awake last night thinking about this problem it was bugging me, and I remembered that a number of years ago I had changed the air quality sensor for one of the cheap Chinese branded VW ones that had been recommended on this forum, it has/had worked without fault until I saw this code yesterday, luckily I had kept the old faulty genuine Volvo one, so popped out the Chinese one and put the duff Volvo one in, cleared the fault codes and hey presto hot air passenger side and heated seats, result!
Not too sure what had been going on, still don't understand how the sensor affects the seat and air temp' on one side only, can only assume the cheap sensor has been creating all the problems with rogue signals.
Must recommend Simon at XC90 heaven in Warrington for good prices/quick service.
If anyone needs a stepper motor part No 30676510 or seat module part No 30710362 give me a shout, going cheap not needed now.
Just thought I would post this in case somebody is having similar problems to help them, after all it what these forums are for, to help/inform.

Thanks for the advice. Presumably you still need a new air sensor, as the original one is now back in the car? You must hardly drive the car with mileage like that :).

Yes you are right, don't use it too much, it had 19000 on when I bought it.
It does need a new sensor, but for the price of a genuine one, I will put up with that feature not working, I'm quite sure there are lots of older Volvos running around with that sensor fault.

Is that sensor easy to install?

Quite easy, it's located in the main air intake passenger side, fiddly but easy, remove wiper arms then unclip plastic scuttle panel (6 clips) under windscreen, then black plastic shroud over intake, look into intake you will see fan at bottom, if you feel at the front (engine side) in air intake you will feel sensor, it turns 90degrees to the right to release, a bit like inserting a light bulb, make sure you remove fibre washer off old sensor and refit onto new one, otherwise it's not a tight secure fit.
Sounds complicated, but once you see it, it makes sense.

Hi there,

I am having the same problem with the cold air & no heat to passenger side seat?

I bought and fitted the Chinese air quality sensor but its not changed my issue?

I've not tried anything else so any advice would be really appreciated!!

Thanks!
Brian.

P.S Its a 2005 XC90.

If it's the same fault as mine, put the duff original Volvo sensor back in and see if you get heat then.
On mine, the fault code for the air quality sensor didn't come up very often, even though it was obviously faulty.

Hi,

I'm having a remarkably similar problem
- heated seats not working (power conning to the seat, have tried all the usual tricks)
- no passenger side adjustments (heat or direction) working
- driver side adjustments fully operational

Do you have the part number for the air quality sensor?

Cheers,
Joe

Before you buy a new one unplug the existing AQS.
If the other faults go away once the AQS is unplugged, you know it is the AQS killing the LIN bus and causing the problems

Then look for a new one...

Just noticed my old post had resurfaced, I’ve still not bothered replacing the AQS (still running with the duff one I put back in) over two years ago.

Seat and heating all ok.