Endeval Posted February 7, 2023 Share Posted February 7, 2023 Hi all, 2013 A6 C7 Avant, 2-zone heating. Problem: No heating/hot air normally. Intermittent issue, rarely works. When driving, I have tried all combinations to get hot air without luck - A/C on/off, shuffling through blowing directions, hot/cold/max-hot, recirculate, windscreen, turn off/on, etc. When the issue happens, the flow and return heater hoses to the heat core/matrix is warm, with the left-side flow hose hotter. I have found on a number of occasions that starting the car again 30 mins later, the heating would work perfectly well, full heat at max blower. Example, I drive somewhere, park and return - heating is OK - but again intermittent. Yesterday while about 30 mins into my journey with just cold air, I turned off the system for about 15 mins. I then turned it on and had full heating, controllable from cold to hot. Starting the car, I don't hear any clicking, etc which might suggest a stuck or slipping blender. If I turn temps to minimum while on auto, I can hear re-direction, cold air and increased flow, so it *seems* thermostats are working (?). Leading up to this, when adjusting direction from auto to windscreen, the screen would fog up heavily, as if there was water/moisture held. Probably a red herring, but said I would mention it. Heater solonoid/valve? Bad Relay? All ideas welcome, please! Quote Link to comment Share on other sites More sharing options...
audia4b5kev Posted February 7, 2023 Share Posted February 7, 2023 SLOW THERMASTAT Quote Link to comment Share on other sites More sharing options...
a6blacked007 Posted February 13, 2023 Share Posted February 13, 2023 Air in system Quote Link to comment Share on other sites More sharing options...
Endeval Posted February 26, 2023 Author Share Posted February 26, 2023 Hi all Coming back to this now....I did some more testing. I could be driving for an hour or two, still cold air.... if I turn off the car and ensure ignition is out and all off (open drivers door), when I restart the car, most of the time, I will have warm air almost immediately. Is there a chance it could be the hot water solenoid (heater control valve) gone or electrical issues? p.s. my car never hits 90c water temp, about 75c - that could be coincidence, maybe a faulty temp sensor? thanks! Quote Link to comment Share on other sites More sharing options...
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