Endeval

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!

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!