A6 / S6 (C5 Platform) Discussion Discussion forum for the C5 Audi A6 and S6 produced from 1998-2004

No heat at all and its the middle of winter

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Old Jul 13, 2018 | 02:46 PM
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Default No heat at all and its the middle of winter

Just bought my 2003 A6 V8 4.2L Quattro C6 sedan but can't get the heater to work at all. Setting temp to high makes no difference. The coolant overflow tank has a bit of brown crud stuck to the sides so I am guessing the HVAC valve may be stuck, or interior radiator clogged.
What is the procedure for determining the fault ?
Where is the HVAC valve ? I can't locate it.
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Old Jul 14, 2018 | 03:30 AM
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Start with the basics; bleed the cooling system.
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Old Jul 14, 2018 | 05:34 AM
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Originally Posted by 4Driver4
Start with the basics; bleed the cooling system.
Did that already, but hasn't made a difference.
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Old Jul 14, 2018 | 04:58 PM
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Originally Posted by georgeb944
As far as I can tell by looking at the Bentley manual and the parts catalog, there is no valve to control the coolant flow to the heater core. So, if the heater core is not plugged, coolant flows freely as pumped by the water pump. The temperature is controlled by electric motors connected to air flow flaps. The motors are controlled by the Climate Control Module, which can be diagnosed with VCDS.

To check if the heater core is clogged, use an infrared temp gun to see if the inlet is hot and the outlet temp is as hot. Unless you are pumping hot air into the cabin, those temps should be about the same.
Thanks for that George. I will check it. That changes my whole approach to the problem. That could also explain why I had difficulty in finding the valve (I assume you meant to write "Audi" and not "Bentley").
I would also like to buy a manual. Anything online that you know of ?
Regards Peter
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Old Jul 16, 2018 | 01:46 AM
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Thanks for that. Its all been an education and on a very steep learning curve. I think it would be better if I study the Manual BEFORE I do any work.
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