A6 Climate Control/Heating problem

[Arsecati]

Hi all, hoping someone can help me!

I have a 2006 Audi A6 Avant with the dual climate control. Problem is, it is intermittently blowing cold when the heating is set to high. If I am driving at a steady pace, like on the motorway - the heating will start working, but slow moving or around town - nothing but cold air coming through.

I did a VAGCOM check, and it's giving me the following message which I believe it may be related to:

00739 - Coolant Circulation Pump (V50)
001 - Upper Limit Exceeded - Intermittent

Tried googling this, but can find nothing specific at all, and really don't want to take it to a dealer (Irish Audi dealers are probably the best paid in the world!!).

Cheers all,

Garry

[portovechios]

Pointing towards a water pump failure, but quite rare in a newer model like yours.

Does the temp guage get up to 90 fairly quick, and sit steady?

Not knowledgeable on your model but unfortunately for most vags the pump although cheap to replace the part but the labour is around 2.5 hours.

If it is the pump then consider a new cambelt/tensioner also if its due within the next 15k as the same parts have to come off to do it.you'll be looking at £230 for the pump or £350-£450 for pump and cambelt.

As i've said i dont know your engine so could be wrong but i'm sure someone will have more to say

Please keep us up to speed, very common faults these and always useful for others

[Arsecati]

Sorry mate, nothing to do with the water pump - the heating has a mind of it's own, can blow hot out one side and cold the other. I'd guess it is a sensor issue somewhere: heating will stabilise on long, steady speeds, but once start slowing down or driving around town, completely random heating again. Cheers for the reply anyway! :0/

[apole]

Hi,

Not sure this applies to the A6, but some cars have an additional electric circulation pump in the circuit to aid flow to the heater matrix. If the A6 has this (and I'm not sure it does) this could be what the error message is referring to.

With the split system I would guess it would have a seperate heater matrix for each side.

Hopefully someone who knows this will be along soon to comment, but just a thought.

[apole]

Just found this:

http://www.audi-portal.com/en/diagnostic/actuators_18773.html

V50 seems to refer to right heat regulation valve connector.

[kite]

Not sure if this applies to your car but there was a fault with a valve on the heating in A6's try having a search.

Sent from my GT-I9100 using Tapatalk

[byronjohnson]

hi

I have a problem with my AUDI A6, that exactly matched the problem you have described

would be grateful to know if you ever got to the bottom of it and what the problem was?

thanks

[Arsecati]

hi

I have a problem with my AUDI A6, that exactly matched the problem you have described

would be grateful to know if you ever got to the bottom of it and what the problem was?

thanks

After 3 or 4 years of sporadic heating, suggestions for everything from new water pumps to heater matrix's, it turned out just to simply be airlocked!! Couldn't believe it and felt a complete plonker after I went through the procedure and got greeted with consistent hot air within minutes of starting the car!

Basically, run the car to operating temperature (even take it out for a drive), then with engine running, SLOWLY loosen and remove coolant filler cap. You may have to do this a few times, but this procedure effectively forces all trapped air to the coolant bottle and is thus released when you open the cap.

I honestly couldn't believe it was this simple, as even talking to apparent Audi 'experts' over the phone about it, nobody could come up with a solution. One 'expert' said he had heard of the problem before, but the guy just go so frustrated, he ended up selling the car instead of finding a solution.

Do I still feel like an idiot? Yes, yes I do - but I did this about 6 months ago, and it has been faultless ever since (even though I still feel like a complete chump when the car is toasty warm within 5 minutes - even stuck in a traffic jam - and I could have saved myself 3 freezing winters, just by releasing the filler cap!) ;)

Hope that helps!

Garry

[byronjohnson]

thanks for the swift reply

my car has been with a mechanic, had the pump replaced and they've tried all sorts over the past 6 months including 'flushing the system out' (whatever that means) surely any air locks would have been gotten rid of during this process?

any thoughts would be appreciated

[Arsecati]

thanks for the swift reply

my car has been with a mechanic, had the pump replaced and they've tried all sorts over the past 6 months including 'flushing the system out' (whatever that means) surely any air locks would have been gotten rid of during this process?

any thoughts would be appreciated

You'd think!!!!!!!!

I've changed the Coolant Circulation Pump, thermostat, full flush - the lot, but unless the 'flush' is done via the 'vacumn process' (the crap I've learned trying to pin this problem down!), the possibilities remain that air can be left in the system, and in my case, there still was, and it was trapped in the heating system!

As I said, I spoke to two Audi 'Experts', one just kept saying I needed to bring it in for a full diagnostics (even though I had already run my own VAG-COM on it!), and the other who suggested changing the water pump and belts was the one who relayed the story of a previously frustrated customer who just ended up selling the car!!!

Incidentally, even though for all those years I kept getting that error on my VAG-COM readings, just last week I ran another (looking for an errant parking sensor issue!), and that error has now gone also.

Trust me, this wrecked my head for years, but that simple procedure corrected it - and even now, I still cannot believe that was the solution, taking literally less than 20 minutes - and only taking that long as I was waiting for the car to get to temperature!

On top of that, it didn't cost me anything - so what else have you to lose but try it? Wouldn't surprise me at all if a mechanic's attempt at 'flushing the system' didn't leave even more air in the system!

[byronjohnson]

brilliant, thanks so much for that, will try it later and let you know

[Arsecati]

Please do - I'd love to hear how you get on! I'm keeping my fingers crossed for you!

[byronjohnson]

hi just thought I'd update with exactly what ive done

drove the car for 20 mins, motorway and around town. parked up, left the car running and slowly opened coolant cap, heard a fizz as though air was being released and then coolant spilled.

I then sat in the car for 2/3 mins to see if heat changed, it didnt.

Left the car for a couple of hours and repeated again, no change in heat.

In the meantime i have told my mechanic about your suggestion and he is going to try and obtain a vacuum bleeding tool to use on system.

will keep you posted
thanks again

[Arsecati]

hi just thought I'd update with exactly what ive done

drove the car for 20 mins, motorway and around town. parked up, left the car running and slowly opened coolant cap, heard a fizz as though air was being released and then coolant spilled.

I then sat in the car for 2/3 mins to see if heat changed, it didnt.

Left the car for a couple of hours and repeated again, no change in heat.

In the meantime i have told my mechanic about your suggestion and he is going to try and obtain a vacuum bleeding tool to use on system.

will keep you posted
thanks again

Ahhh bugger, was really hoping this would work for you! Really sorry it didn't work for you - it's problems like this that make me hark back to the good ol' days of simple mechanics, when something like this could have been solved with a lump hammer and some gaffer tape! :0/

I'll keep fingers crossed your mechanic can sort it via the vacuum method then - let us know how you get on!

[kite]

Have you seen this thread.

Air con blowing hot on passenger side (http://www.vwaudiforum.co.uk/forum/showthread.php?t=165835)

[dan2485]

Opening a hot coolant expansion bottle is very dangerous and should not be recommend as a way to bleeding the system.

The correct way is to use the bleed screws on the pipework/ radiator.

[dan2485]

Have you got the centre vents in the MMI set to cold?

[byronjohnson]

mechanic performed vacuum bleed of the whole system and it now works perfectly

really appreciate you coming back to me on this one, had completely run out of options

cheers

[Arsecati]

Not a problem at all my man! Trust me, I know exactly how you were feeling - so delighted I was able to help! ;)


mechanic performed vacuum bleed of the whole system and it now works perfectly

really appreciate you coming back to me on this one, had completely run out of options

cheers

[audia62.7]

Hello. The error code that you have on the circulation pump indicates that there is air in the system. Nothing wrong with the pump. Because of air in the system, so the pump go much faster. It is because of that error code is added.

Some are very difficult to air bleeding, Thinking you have to stand on 1800-2000 rpm for the air is out. may take up to 4 hours.

Run the engine warm, parks flat or with motor at the highest point. Remove the lock of the expansion tank slowly. Fill up the tank for and so keep the car on 1800-2000 rpm that the air is gone. make sure the tank is constantly full.

Stian, Norway

Google translate; D

[Pudsey Bear]

Hi, We bought a used A6 a while ago and it has this stupid problem, I have only tried releasing trapped air via the expansion bottle once so far, this was yesterday, I have to go out later so I'll try it again and report back.

In the meantime has anyone else had the same problem and cured it the same way since April 2015.

Cheers Kev UK.

[Paomax1]

Hello i have same problem 2017 audi a6 cold air comes in after a while hot in one side n cold in the other finally i get hot air don’t know what it is let me know if u solve problem please

[Vanjapet]

Hello. I had same problem with my Audi. In the beginning the engine thermostat was damaged. After changing the engine temp was ok but there was almost no heating at all. After days of bleeding and checking dismantling solenoid valves I found out that the cooling system was sucking air from bad seal on bleed screw. After that I followed advice from the forum. Parked the car up the hill engine forward opened cap on the expansion tank and miracle happened. Immediately I could hear bubbles coming out on the outlet pipe from inside heater. I kept rpm at 2000 for 10 min and after the engine reached 90 degrees. All good now. Hope this helps.

[HydrocarbonPrim]

Hi fellow A6 owners.

I know this is an old thread but i've had a similar problem with my 2.0 tdi auto c6, I recently bought the car and found it would not get upto temp in very cold weather (-3.0) on my 17 mile commute. In weather over 10 degrees it get upto temp, anyway I bought 1x non return valve, a main thermostat and a small thermostat that sits above / below the non return valve pipe that goes to the oil cooler (near the bulkhead / back of engine)

I Installed all 3 and refilled system with antifreeze and de-ionised water and still have exacly the same issue, I also noticed it didnt seem to require much bleeding for there to be heat in the cabin, however it's not achieving constant 90 temperature. I do notice minor heat fluctuations when going over bumpy roads, so after reading this thread I'm hoping my issue is just trapped air, but any input is welcome.

Does anybody know where the auxiliary / parking heater is fitted on models that have it? I have it enabled in mmi but don't think i actually have one, apparently there is an electric heater core for demisting on Some models.