Auxilary Heating

[Mitchet]

Just thought I'd share some interesting VAG-COM coding for the auxiliary heating system.

I always wondered what module 18 (Aux Heating) was for in my 2005 A8 3.0TDi, and apparently all common rail diesel Audi A8's (and Q7's) have some form of auxiliary heating installed. This is due to the cooler running temperature of the modern diesel engine, which can result in the engine temp not reaching its optimum value.

I'm not quite sure how much of the aux heating system is installed by default, as the full system includes (I believe), a second battery, a Webasto fuel heater which is connected to the main fuel tank, the aux heating module and a shut-off valve. Any more suggestions or corrections are welcome

The shut off valve limits the cooling circuit to only heat the cabin, meaning that during the winter, with the aux heating system operational, cars without the shut off valve will take longer to warm up inside, as it's also heating the engine.

Anyway - the coding

Module 08-Auto HVAC > Coding - 07 > Add 2 to the current value (make sure you note the original code in case you need to revert back).

Not sure if this next step is needed, but go into the hidden MMI menu (press and hold CAR + SETUP for 3 seconds), select "DIAG SETTINGS" > "APK 0x01, 0x0B, 0x0C", scroll down and tick the box for Aux Heating. Scroll down to the bottom of the menu and select "Accept Changes".

Turn off ignition, disconnect VAG-COM, and (restart MMI if necessary).

You should then by able to access all the Aux Heating controls through the climate control menu using the SETUP button on the climate unit (not the MMI SETUP button).

Options are listed for Aux Heating / Aux Ventilation (runs the fans at low speed to help cool the cabin down during hot weather). Plus, 3 timers are available for turning on the aux heating / ventilation system at a preset date/time.

Also note that if the outside temp is high (not sure how high!), the system will only operate in ventilation mode with the heater staying off.

Should fuel level fall below quarter of a tank, or the battery fall below a certain level (11.65v ?), the aux heating system will automatically shut down.

Many thanks to Neo_Andersson on audiforum.us for his information on this system as fitted to the Q7.

Edited August 17, 2010 by Mitchet

[Wizbit]

Sounds pretty cool. Does it actually do anything then on yours now you have it enabled?

You mentioned the full system has a load of other parts needed (second battery, webasto heater etc) ...

[Jetinder]

That's very interesting. I was looking through my D4 manual the other day and there's a section about setting up the auxiliary heating/cooling via the keyfob. The keyfob itself is different as it has a little lcd display where you can set the 2 timers for the aux heating stuff i.e what time do you want it switch on and to what temperature and for how long (it cools/heats the car to a set temp via this prior to you even being near it).

I asked my dealer why I wasn't given the option to order it, he didn't know and the techs haven't got much info either. I might have another chat with them.

cheers

Jet

[Mitchet]

I've tried it with the auxiliary ventilation, and it all appears to be working fine. I set timer 1 two minutes ahead of the current time with the ignition off. When the timer elapsed, the climate panel came on with the blowers on low speed.

I can't try the aux heating at the moment, as the system uses the cars temperature sensors to determine which mode is required. If I try to use aux heating with the outside temp being 20c, it won't function (fair enough really!).

From the Q7 guys on Audiforum.us, it seems they have all the components aside from the cutoff valve which controls the cooling fluid circuit. Perhaps at the weekend, I'll have a sniff around the engine bay to see if I can find the Webasto fuel heater.

I don't think Audi offer it as an option in the UK. Apparently it's only available to countries with colder climates... which is odd, given our last winter!!!

[Mitchet]

Oh - and the system for the D3 also supports aux heating / ventilation via a keyfob, but that requires a few more bits (though it simply has an on/off button for the D3 model).

[untruenorth]

I believe the Webasto is a round jobby towards the back left hand side of the engine bay, as you stand at the front. It's got a couple of pipes going in and out on the top side of it, and - I'm guessing - more gubbins underneath.

I got all excited about this when I first saw it, as I remember the brand from BMW ownership days and thought "oooh, aux heating".

Since you've had some luck with aux ventilation, I'm very interested in finding out if I can at least get that working. Just the ventilation is a huge win in summertime even if the heating can't be made to work in wintertime.

[Mitchet]

Just noticed when filling up the screenwash at the weekend... the car definitelty has the Webasto fuel heater installed, as the label is on the underside of the bonnet!!!

Bring on the cold mornings!

(see attached)

[brisweeney]

just noticed i had the exact same sticker on my bonnet, so does this mean that all parts for the aux heating are installed and it just needs some one with a vag-com to code it in?

i know on bmw x5's the webasto was nearly always installed,but the option of having it functioning was an optional extra, charged at what ever price they wanted!

so if anyone knows if its just a case of coding then ill be finding a friendly vag-com equipped garage! do you have any more info on how it can be used via the key fob?

[Mitchet]

The coding instructions are in my first post ;-)

Not all aux heating parts are installed (see my first post again), the key fob will require more parts.

[eldavo69]

The wife's old X5 had aux heating and I was very jealous as she stepped into a warm and defrosted vehicle on cold winter mornings whilst I was busy with the ice scraper on my A3.

[Alister]

Did this mod actually work in the winter? I started investigating this yesterday and then as if by magic another post appeared http://www.tyresmoke.net/forum/audi-a8-s8/134612-definitive-guide-installing-auxiliary-heating-your-a8-d3.html with a longer guide. I notice that this thread is old and was created in the summer – How did you get on when the temperature dropped?

The other post suggests that a recirculation pump is required for when the engine is not running. I am not over fussed about heating the engine or remotely controlling the heater just setting it, taking the chill of the cabin and defrosting the windows – If I can get away with a VAG-COM modification only that would be best. Does what you guys have done achieve this? Have you had any problems with it to date? Flat batteries?

I’m mechanically inept so am just looking for if it works and then if I can pay someone to set the VAG stuff – again recommendations on who in the North West would also be appreciated.

[Ridley Scott]

You need to fit the recirculation pump to create a flow thru the Aux Heater to heat the water otherwise there is no flow and the water will over heat and shut the heater down.

[TrollTor]

I am wondering about the T91 kit.

There is one set that have a white box, and one set that have a balck box.

(links to the sets on ebay)

 

The black one says T91/T100. I guess I should go for the white box?

 

Also it says:

IMPORTANT Before you plug the main connector back into the FBH you need to introduce a wire to Pin 1 of the main plug.

Did you cut and solder this one on to the wire the behind the connector?

http://www.ebay.com/itm/NEW-OEM-VW-WEBASTO-CONTROLLER-TELESTART-T91-FULL-SET-5Q0963513-A-5Q0963511-/131702883400?hash=item1eaa1a8448:g:zYsAAOSw5dNWmqZL

 

http://www.ebay.com/itm/TELESTART-T91-T100-Fernbedienung-Satz-fur-Webasto-THERMO-TOP-remote-control-/142309078466?hash=item21224835c2:g:sgoAAOSwzgBYw96M