Early A6, heat not getting in to cabin :(

**Mr Footlong** · 02-03-2009,02:42 PM

Hi folks. Sorry, first post and all that but I am a Subaru nut whereas my folks are Audi nuts. I am coming here to ask for help from you fine folks regarding my Mum's Early (1st revision A6, N/P reg if memory serves) and the total lack of heat coming in to the cabin regardless of how long a drive you go on.

First I will bore you a bit with previous problems. The car had been overheating constantly in traffic and her muppet of a mechanic couldn't find the problem no matter what he tried according to him. Gave the car to me and 1 £7 cooling fan temp control switch later and that was sorted, shocker.... What I wasn't prepared for was the fact that it looked like the car had NEVER had it's coolant changed (over 100k miles and a fair few Audi services) and what came out was like nothing I had ever seen come from a working engine before. the system was full of pure brown rusty water and simply full of large rusty debris. It took 6 full flushes by me over most of a day and the necessary amount of G5+ additive to make it look perfect again and still looks cystal clear 2 months on.

What concerned me is the other problem she had, the cabin heating was still almost stone cold regardless of the temp set inside but based on what I saw come out I considered that the heater matrix could well be blocked. I popped the top back of the bonnet compartment and was very happy to see pretty well all the cabin heating/cooling bits were external to the cabin! I have checked the valve everyone talks about and the vacuum line is working correctly and makes the valve arm move up/down. The A6 has this controller in the dash: http://ftaclan.net/clanftp/nick/mumaudi/IMG_0792.jpg

At 'LO' setting on the controller the valve arm is totally down and anything other that 'LO', the arm is all the way up. The pipe is very warm either side of the valve and I have felt the pipes where the enter/exit the core and while not nearly as warm as by the valve, they are at least warm to the touch so I think water is passing through the matrix. I am going to flush the matrix this weekend as it would be rude not to seeing how easy it is to get to. Here is a pic of the heating/cooling area: http://ftaclan.net/clanftp/nick/mumaudi/IMG_0793.jpg

What concerns me is the little plastic arms/wires linking them all together to the left of the heater matrix assembly and their lack of movement. I am assuming that they basically control a panel/panels behind the matrix that allow air passing through the matrix to enter the cabin? No matter what buttons are pressed/temp set on the controller, these arms/rods do not move at all. I have tried coaxing them but can see something going snap far too easily. I have circled what I am on about in the pic here: http://ftaclan.net/clanftp/nick/mumaudi/IMG_0794.jpg

If you guys with all your A6 experience could give me your opinions/advice on this one I would be so grateful. The only thing I haven't got around to checking yet is fuses to be honest but I wouldn't expect there to be a fuse just for controlling whatever controls those flaps, could be wrong though!

Cheers,

Nick

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**Peter D** · 03-03-2009,12:38 PM

Did you back flush the heater matrix. Regards Peter

**Mr Footlong** · 03-03-2009,12:57 PM

Hi there. I will be flushing the matrix as fully as possible in both directions this weekend but I still don't think that is the issue due to the fact that the linkages on the side of the matrix housing (3rd picture) do nothing regardless of what is set on the climate controller.

Cheers,

Nick.

**Peter D** · 03-03-2009,01:01 PM

What year and engine code is the car. The code is on the ID label in the sevice book or in the spare wheel bay. Regards Peter

**Mr Footlong** · 03-03-2009,01:06 PM

At work at the mo so I will have a check when I get home and let you know. Thanks

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**Mr Footlong** · 04-03-2009,11:16 AM

Sorry, could only get to it this morning. It is a 4A revision and I really don't know what year but it is the very first revision of A6 where it looks more like a late Audi 100 if that helps. Also it has the older style 4 pin ecu data connector if memory serves, not OBDII.

Cheers,

Nick.

**Mr Footlong** · 22-03-2009,09:40 PM

Right, well I made a lot of progress on the heating and got that all working, or so I thought but have had another nasty problem come up but I will talk about that in a mo. After playing with the climate controls and watching the lack of temperature flap movement by the heater matrix I ran the diagnostics on the CC and it confirmed that there was a problem with the motor/potentiometer.

Bought a new one and fitted it yesterday and was over the moon when that problem was sorted. Heat still wasn't getting in though. The hot water valve to the matrix that I had checked, was working, but due to mum's mechanic' playing' with the vacuum hoses, he had managed to wire them back so that when coldest temp was selected the valve opened and on anything above coldest it closed the valve! I looked on google but in the end managed to put the 3 pipes back in an order which appeared to work correctly. I now got warm air through in to the cabin as expected.

Now, the engine had been run up to hot (45 mins- an hour I would say) and the cooling fans were kicking in when needed and I took her for a run and all was well so I turned her off and declared her fixed. Mum picked the car up today and I followed her back in mine. In under 8 miles at about 70ish for the most part, steam started pouring out from the expansion tank side and I pulled her over

. Let it pressure down via the cap, poured about 2.5 litres of coolant in and tried to crawl the last 3 miles home but had to stop again to be safe with steam coming out again and picked up after it had cooled.

What on earth could be causing that now? The temp guage showed normal, the cooling fans were not kicking in at all. I had noticed a light 'mayo' coating on the oil filler cap yesterday morning just affter starting up but the car hadn't been run for a couple weeks so cleaned it and checked again, it didn't return. If the vacuum hoses on the cabin heating system are still the wrong way around could that be causing the problem or just a coincidence?

If somebody with my version A6 could take a couple of pics of the tubes on the drivers side by the Windscreen wiper motor so I can compare I would really appreciate it!

Thanks,

Nick.

**Mr Footlong** · 23-03-2009,12:58 PM

Please, anybody? I am not fixing this car by choice at all. My mum hasn't got the money currently to get it fixed by Audi and that leaves me stuck with the problem

Thanks,

A desperate Nick

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**Peter D** · 23-03-2009,01:16 PM

When you filled the car with coolant did you lead the air from the system. When the engine iss cool/cold, release any pressure form the header tank, start the engine and run at 3000 rpm for 30 seconds. turn it off and chech the hosses for pressure, if they are rafther firm then you may have popped a head gasket. If you have a loacl independant garage nurse it round there and get the gasses sniffed in the header to confirm, or not as the case may be. Regards Peter

**Mr Footlong** · 23-03-2009,02:04 PM

Hi there. The thing is that I didn't have the time to actually flush the coolant that I was planning on doing after fixing the heating. No coolant pipes were disconnected/reconnected at all. I didn't disconnect the matrix pipes etc either. The fluid in the cooling system is exactly the same as was put in 6 months ago by me and has run without fault, up until yesterday!

Does that help narrow things at all? Also if anyone could take a pic of those vacuum pipes I would really appreciate it!

I have included 2 pic of the bits that I would really like to see pictures for is poss:

http://ftaclan.net/clanftp/nick/mumaudi/DSC00204.JPG

http://ftaclan.net/clanftp/nick/mumaudi/DSC00204.JPG

The red circles show the bits I am on about.

Thanks,

Nick.