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

[rjtire555]

Hmmmm...

I unplugged the factory fitted AQS for the first time last night and my functions didn't return. Heated seats still lighting up but not heating - I didn't drive the car for long enough to be 100% sure but I think the passenger side is still hot and the driver's side cold. Bummer.

Using a multimeter, I can see 14V at the heated seat controller under the driver seat but I'm getting 0V on the outputs when the engine and seats are switched on. The impedance of the heating pads in the seats is circa 1ohm so they seem fine. I also bought a replacement controller from Skandix but changing that doesn't change anything.

I've ordered a new Volvo replacement AQS for £60 off eBay. Will try putting that in but I'm less confident that this is my fix now...

Do you need to clear any diagnostics to reenable the functionality?

Thanks,
Joe

[SwissXC90]

Originally Posted by rjtire555

Do you need to clear any diagnostics to reenable the functionality?

No.
Almost every system is self-healing when you repair the fault - that means, it runs properly again once the fault has been physically repaired, regardless of whether a fault was previously logged.

The only exception is the critical lifesaving system: the Airbag system.
The Airbag system will log a fault if it detects anything wrong, and will NOT clear the fault alarm when the fault clears. You need to use the diagnostics to clear the airbag fault alarms.

But seat heating is very non-critical, and will come back to normal operation once the fault clears.

At this stage you should stop throwing parts at the system and get Volvo VIDA diagnostics connected. VIDA will tell you exactly where the fault lies and allow you to make a much more rapid diagnosis and repair of the problem.
See if a friendly forum member with VIDA is available in your region of the world for a cup of tea, a biscuit and a diagnostic session.

[rjtire555]

Thanks for the advice and the sense in the message.
I've been enjoying taking bits of the car apart but my skint knuckles and paypal balance agree with your summary.
I had been considering buying a VIDA setup for some time. I've PM'd one of the folks who sells the DICE/VIDA setups on here to see if they have something available. Any suggested contacts welcome!

[colinbos]

The AQS for Volvos are a funny peculiar item.

Mine has shown as amber warning in Vida since I bought it. That means it has not function for some ion the time in say 100 tests. ALL my seat heating, air con works etc. So, I bought the correct one from Volvo, to have the car exactly correct.

When I fitted it, the air con and seat heating went BONKERS !

I rang Volvo, they assured me I had the correct one, even sent me another in case the first one was faulty. The 2nd one was just as bad. So i refitted the 'broken' one and haven't had a problem since.

I still have the amber VIDa DTC showing that it isn't working all the time. but with no other problems.... Im not doing anything about it. No one would ever know.

[SwissXC90]

And conversely: when I bought my car 2 years ago I had an AQS faults

Cleared the alarms, came back

Started maintaining my car well, with new cabin filter and keeping it clean.
No more AQS faults.

Correlation? Don't know.

I last checked my car for faults 2 days ago.
Still no AQS faults.....

[colinbos]

Thats one thing I haven't changed..... Think ill do that tomorrow.

[Piers1956]

Well that was a stroke of luck for me. Thank you. I have spent nearly 2 weeks putting a 2006 V70 D5 back to it's former glory. Too many issues to list but safe to say over 20 fault codes to sift through.

1 of them being 0048 AQS. An old friend my mine and usually ignored as I don't rate the sniffer dog as it prefers screenwash to diesel fumes or London smog. However on this car I wanted to try and rectify everything.

I have failed. 0048 gone but in it's place DD00. SNAP!

Passenger seat no longer heating. Scanner shows driver's seat switching fine as it did yesterday with passenger seat. I'll probably find the cold air left/warm air right later but I drained down this morning for antifreeze coolant change so won't know until later.

Although it might be coincidental I also had codes 6663 6664 and 6665 yesterday. This morning I did a resistance check on all glow plugs and 1-4 were perfect 5 was iffy. I don't have any of those codes but P0000 has arrived. Nothing else touched this morning so has the AQS caused this as well??

I'll rip the scuttle out again in a minute and put an 0048 failure sensor back in. I have 4 of them and now 2 DD00 sensors.

Why don't the con rods just burst through the crankcase and give me something tangible to play with.

Thanks again, it's comforting to know I don't stand alone.

I have changed the AQS over to one with a known 0048 failure code and not a DD00 code. the passenger seat is working again and the blowers are good. For those interested I recorded.

Seat o/s 34.2c (My backside on it)
Seat n/s 28.5c
Floor Vent o/s 31.0c
Floor Vent n/s 31.6c
Face Vent o/s 37.5c
Face Vent n/s 38.3c
Screen Vent o/s 27.2c
Screen Vent n/s 26.6c

The heater matrix on this car was blocked solid with Bars Leaks when I acquired it and has been flushed through with firstly Coke-Cola and then White Vinegar at boiling point. Many times. Easier than removing a matrix from a RHD V70.

Moral to the story...If your n/s heated seat and n/s heater pack up, fit a duff AQS (0048).

[SwissXC90]

Originally Posted by Piers1956

Moral to the story...If your n/s heated seat and n/s heater pack up, fit a duff AQS (0048).

But... with VIDA you can see all of that without removing anything.
And quickly come to the conclusion that the LIN bus is down and the likely culprit is the AQS

[Zchas13]

Just want to thank the advice off this thread for sorting my issue.

2008 d5 xc90 similar issues, non functioning passenger heated seat with no hot air on same side when heating on max.

New AQS from volvopartstrade on ebay for about 85quid and an hour of my time seems to have sorted it.