Sulphur smell coming from vents

[Itsrainman]

Hello, I have recently purchased an A6 Avant 2014 pre face lift. It has the 2.0tdi engine with the auto gearbox. Full service history. Milage is currently 74000. Over the last week there has been a sulphur smell coming from the air conditioning. MPG also appears to have gone down. I have changed the pollen filter just in case but it has made no difference. No smoke from exhaust and smell from there appears normal. No obvious signs of a leaking exhaust. Its booked in to the garage on a Wednesday. Any pointers for me to let them know would be a great help.

Thanks

[Crasher]

Get them to stick a AC cleaner into the air box up the drain tube.

[johnsimcox]

Sounds like it is doing a DPF region.

[Itsrainman]

Thanks for the responses. Ill check on the air con cleaner as it seems to do it if the engine is off. Unless its an after smell still coming through. I do 500+ miles most weeks and its been there for a week so would hope the DPF regen has not stuck on! No errors displayed in VCDS. I’ll google on how to check the status of the cat to confirm if in regen.

[Itsrainman]

One can of detol disinfectant spray into the air-con intake and the smell seems to have gone away. Long journey tomorrow to confirm. VCDS confirms no DPF regen and soot load at 12%.

[Crasher]

That tends to work short term in killing the bacteria that builds up on the evaporator but long term I use half a can of https://eshop.wurth.co.uk/Air-conditioning-disinfectant-spray-DISINFSPR-A-C-300ML/089376410.sku/en/GB/GBP with the tube up the drain pipe and the other half down the intake with the pollen filter out AND I know use the Mann FreciousPlus filters and these help prevent bacteria from getting onto the evaporator, after using a FreciousPlus for a year I have had no repeat of the bi annual pong.

[Itsrainman]

Crasher. I think your right. 300 mile journey today and the pong returned after a few miles. Car is in the garage tomorrow so will see what they say. Hopefully covered by warranty. Where do I find the drain pipe?

[Itsrainman]

Car was in garage today but problems with the gearbox took over. I have also emptied the washer bottle and topped up with water and a small amount of detol. 150 journey tomorrow so whom knows!

Can washer fluid go off?

High concentrate stuff -22 watered down 50/60

[Crasher]

If washing up liquid is put into the washer bottle it can turn rancid and smell like death, the ac drains come out either side of the floor tunnel behind the tunnel heat shield either side of the gearbox.

[Itsrainman]

No smell today. So definitely will the washer bottle. No washing ip liquid just good quality screen wash.

Thanks for all the help.