Audi A6 - Air con blowing very hot

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Thu 4 Aug 2011 22:04
Audi A6 - Air con blowing very hot - Paul77C

Hi

My 2004 Audi A6 (C6) 3.0 TDi Quattro has started to on occasion blow very hot air through the drivers side dash vent and the centre rear vent. The air is so hot that the metal around the vents becomes too hot to touch. It happened first 2 years ago and is now happening about twice a week.

The rest of the vents blow cool air. Changing the temperature on the climate control dials seems to make no difference.

Does this sound like an electronic fault with the control unit?

Any suggestions would be appreciated

Paul

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Mon 15 Aug 2011 21:50
Audi A6 - Air con blowing very hot - Paul77C

It was the Heater Control Valve that was stuck.

Thought I'd have a go at cleaning it rather than replacing; and so far seems to be working....

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Tue 15 Nov 2011 07:17
Audi A6 - Air con blowing very hot - rjm67

Hi,

How is your cleaned valve going? I have the same problem.

Richard

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Tue 15 Nov 2011 12:47
Audi A6 - Air con blowing very hot - Paul77C

Hi Richard

Still seems to be working fine.

Diagram available at www.audi-portal.com/en/diagnostic/actuators_18773....l

The top of the valve is simply screwed on with some Torx fasteners.

Good luck with yours

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Tue 15 Nov 2011 19:09
Audi A6 - Air con blowing very hot - rjm67

Thanks for that. Don't suppose you could tell me what you did could you?

Cheers

Richard

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Tue 15 Nov 2011 22:05
Audi A6 - Air con blowing very hot - Paul77C

Hi

Once the cover was removed there are a couple of small pistons. These came out easily and I just cleaned them and replaced. They look like they have quite tight tolerances and just had a few bits of debris on them.

Just lost a little coolant when taking them out but only an eggcupful maybe?

Paul

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Mon 16 Apr 2012 23:53
Audi A6 - Air con blowing very hot - johnpr

Richard, did you try Paul's suggestion for cleaning the pump valve?

I'm sure my 2005 A6 has the same problem.

If you did try it, did it resolve the problem and did the fix last?

Is it easy to get the pump cover off and back on again? Are there any seals / gaskets which need to be replaced? Are there any small parts that might pop out and get lost? Has it leaked at all since you took it apart?

Thanks in advance for any useful suggestions you have.

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Thu 5 Jul 2012 23:28
Audi A6 - Air con blowing very hot - johnpr
Shortly after posting this question I found an extremely good post on another forum, complete with pictures and very detailed instructions.

Look at the post from rstoer on 15th April 2012 in the following thread

forums.audiworld.com/archive/index.php/t-2756309.h...l

I followed these instructions myself and now have a perfectly working heater again. The pistons in my pump valve had the same gunk on them visible in rstoer's post. I cleaned it off with T-Cut and silver polish. Since performing this procedure the hot air problem has never occurred again. That was over two months ago and I am very happy with the results. I really took care making sure the pistons were spotless, but even though I took my time the whole job was completed in less than 2 hours with absolutely no leakage or mess. It also saved me approx £450, which is the cost of a new pump valve and getting it professionally fitted.

Replacing the whole pump valve unit is very tricky and I did not want to tackle it myself. Removing the top of the pump valve unit and cleaning the pistons is incredibly simple and works a treat.

Great post rstoer!!!
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