But do you think that if one of the motor went bad, I wouldn't get an error through scan? Should I change it anyway just to see if that solves it?
You might not see an error, sometimes the plastic linkage arms break as well. Ideally you need to start taking your dash apart to check all the linkage arms and actually see if all the motors are working, but that is a pretty big job because the motors are dotted about in different places and most of them are very hard to get to. This is why I've given up with mine for now.
I just took out my glovebox today, everything seems to run just fine from that side. I don't really know what to check anymore. Through OBD11 all the flaps seems to turn normally but I think it only register the motor from the glovebox side, not the actual flaps
Well let me know if you ever figure it out because the only possible solution I have at the minute is giving Audi an open cheque and an unlimited amount of time which I'm not prepared to do.
On the A6 there used to be a common fault where the drivers side vent were hot and the passenger side vents were cold, it was not caused by the distribution housing inside the car, it was a fault with a coolant valve inside the engine bay. The fault happened on my C6 and after replacing the valve the temperature was normal again on both sides. Maybe worth looking at the A3 coolant system diagrams to see if there is a similar valve system on the 8V models. This what what the valve unit looks like on the A6.
I don't know if my recent experience will help, or even if it's relevant, but I was having a problem in my S3 with lack of heat, even when it was frosty outside. Turned out to be a defective valve: Part No. A4HO 121 671 D 'Coolant Pump/Valve' (£116.58 + labour + vat). I always have the right hand A/C knob turned on 24/7 (stops misting up in winter and keeps things breezy in summer) and the left hand Auto knob I also have turned on and let it do its own thing. The passenger side is set at 74 degF (the wife's a chilly mortal) and my side at 70 degF and, since the fault was rectified, we've been perfectly comfortable once again.
How can I check that? Through VCDS or OBD11? And where exactly does it go in the bay? I looked but no luck..
Not sure if your question is for me, Alin, but I'm no expert unfortunately. I find that if you press in the left hand knob so that the red light in the centre comes on, that seems to get the system to call for heat up to the temperature chosen by the individual thermostat knobs. Not all versions of the A3/S3 have the same heating & ventilation panel though, so a quick read up in the manual might also help. This pic is borrowed from elsewhere, so not mine, although the same version as in my car (I never have understood what 'eco' setting means!):
According to http://www.manualesaudi.com/AudiA3/en_GB/onboard/o_m00248.htm The "eco" mode*1) is activated if you press the AUTO button briefly while automatic mode is active. Fuel is saved in "eco" mode* because the settings respond more passively. The "eco" mode* is on when eco appears in the console display. The "eco" mode*is deactivated when you press the AUTO button again
Appreciate the guidance Craig, thank you. If the settings 'respond more passively' in eco setting, what exactly happens? Does it just take longer to adjust to temperature variations, or what?
That I got it but I just can't seem to find the control valve in my engine bay. There are no diagram for this, I looked for days...
I don't think the S3 has such a valve, I believe all the 'mixing and diverting' of hot air is done in the cabin via the heater flap motors rather than a valve in the engine bay diverting hot water into the cabin, I'm pretty sure hot water is piped into the cabin permanently and then distributed as required by the heater flap motors. I may be wrong of course. FYI I still have the some problem, I'm currently unemployed again due to COVID so I just can't justify giving an Audi an open cheque to sort it out.
You are correct in relation to the 8V platform not having individual heat exchange valves. The ones pictured above are for the A6 which has a 2 zone heater core. The valves limit coolant flow to each side of the heater core depending on selected temperature in each zone for that system. For that platform they have been known to hold air pockets and seize up. We do have valve in our system which controls coolant flow to our single zone heater core (component 10 in alpesh26's link above). This is used to divert coolant to the rest of the engine if not heat is requested by the climate control head. As mentioned in a previous post, this valve may be a culprit but symptoms would be no heat out of all vents or limited heat but equal across all vents. These N82 valves have been known to fail and let coolant into the connector so may be worth checking to be safe. If you are experiencing issues with just one vent, it is most likely due to a temp sensor or flap motor inside the cabin. I would also make sure you verify the issue with the climate system set to Auto and Eco mode turned off. If you still have an issue, check faults and see if there are any range faults for any flap motor. There have been cases where these flap motors can freeze up. I would run the basic setting (via VCDS) to relearn all flap motor end stops and see if that fixes the issue. If it returns, most likely you will need a new flap motor. Lastly, the temp sensor in the ducts can give a false reading (I have not seen this though). Simply run the system as above and use a temp gauge in the vent outlet. Compare your reading to what the measuring values are reading in the climate control head. VCDS will be your friend here as it can help you complete the above diagnosis. Hope that helps you out.
My issue is the passenger vent blows quite a lot hotter than the drivers vent so even with the climate set to very low the passenger side always blows warm/hot (not ideal at all in the Summer). Audi re-learned all the motors flaps their start and end points which made no difference and they didn't see any error codes associated with any of the heating system. I also ruled out the temp sensors behind the vents by swapping them over and still having hotter air from the passenger side.
I see. With all those steps done, one would lead further toward the blend flap motor. One other variable I am not aware of is if Audi has seen this issue and created a TSB or software update. I would assume not as you have brought it down to them and they only adapted the end stops.
The blend flap was the conclusion I came to, it was a while ago now so I may not be remembering correctly but I tried to get at the blend motor myself and simply couldn't without taking the whole dash out but I'm sure I got a torch down the center heater vents and could see the blend flap operating correctly. Whether what I was looking at was the actual blend flap I can't be sure. Unless anyone knows an easier way of actually getting eyes on the blend flap and/or its motor I'm lost for what to do next.
Our HVAC assembly consists of 5 flap motor / position sensor units. There has been some uploads earlier in the thread but for consistency, I will sum up below: 24 - Recirculation flap motor 25 - Right side temp control flap motor 26 - Left side temp control flap motor 27 - Air distribution flap motor 28 - Defrost flap motor Number 25 would be the unit you would want to verify for operation (assuming left hand drive for my documents). You may be able to swap 25 and 26 to see if the issue moves but I am uncertain if the connectors are the same from side to side. Right temp control motor is below the defrost motor: Left temp control motor location: What is interesting is all the flap motors have position sensors integrated inside. If they do not get to their desired spot it should set a fault. I would also make sure the flap door moves freely when the motor is removed. Best of luck.
I have the exact same problem with my 2006 A3 2.0 TDI. Audi has already replaced both flap motors and it does fix it for a bit, but the problem seems to come back after a while. On a lot of forums find to check/replace the position resistance transducer inside the motor housing. They are cheap as chips so will give it a go.
