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Help....my heaters...well...too hot!!

Discussion in 'A3/S3 Forum (8L Chassis)' started by A3Tom, Mar 13, 2010.

  1. A3Tom
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    A3Tom Smell my finger.

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    [Mar 13, 2010]
    Hi,

    Annoying problem has started to occur with my car..

    When I have the heater on about 22 degrees its sooooo hot, like its on high all the time. The only time it goes cool is if I put in on 'Lo'...then its icey cold as normal. No matter what temp I set it to its red hot...grrr :(

    It wasnt too much of an issue in the colder weather but its getting right on my tits now the weathers got warmer.

    I dont know if its connected but there's a faint 'motor/whirring' noise that comes from behind the glove box since the heaters been playing up. It sounds like something is always 'adjusting' itself...kind of like when a CD player 'whirrs' when its trying to read a scratched CD.

    Anyone had any issues of a similar nature as its got me scratching my head and I want to sort it out.

    Cheers

    Tom
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  3. ALPINE
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    ALPINE Yes its diesel, now cry u lost

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    [Mar 13, 2010]
    your little holes are not blocked are they tom? just above the climate unit? Just a simple idea maybe? i know the sensor on the unit controls the Auto function. maybe thats up the creak?
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  4. A3Tom
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    A3Tom Smell my finger.

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    [Mar 13, 2010]
    No mate, all fine.

    Its been doing it since I changed my stat so perhaps an air lock in the heater matrix?. I ran the cooling system with the top off for ages when I did the stat, squeezing all the hoses etc so I'm not sure what else I can do to get any suspected air the f*ck out of my heater so I can get it working again :(
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  5. ALPINE
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    ALPINE Yes its diesel, now cry u lost

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    [Mar 13, 2010]
    if its done it since you changed the stat, then i would say its to do with what ever you have disterbed. If there was an air lock then the car would overheat surely.
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  6. kaizokuninja
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    kaizokuninja Member

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    [Mar 13, 2010]
    May not make a difference but..

    When i used to flush all the stuff on my mini it was recommended to have the heating on and running at full at the time.
    But i digress, this may have been someone talking out of their rectum and me being young and listening?
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  7. A3Tom
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    A3Tom Smell my finger.

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    [Mar 13, 2010]
    Thats what I was thinking, although nothing apart from the alternator wiring harness was moved when I changed the stat.

    All the rad hoses get hot etc so the engines cooling properly. temp sits spot on 90 without fail, solid as a rock etc.

    I'm going to have to get my head into the Haynes manual tomorrow and try and find where the heater pipes go and have a look at them I think

    Its really annoying!
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  8. emery1990
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    emery1990 Active Member

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    [Mar 13, 2010]
    Now you say it, i think mines playing up too, i normally put it on 22, but its just way too hot, then when i puts it on 21 it starts to cool down to a normal temperature that doesnt cook me, but this is with the air con off, which probally makes a huge difference.
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  9. A3Tom
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    A3Tom Smell my finger.

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    [Mar 14, 2010]
    Right this is annoying now, and not something as easy as an airlock :(

    I ran the car up from cold today, cap off the expansion tank and gave all the hoses a good squeeze for about 20 minutes. Coolant is circulating as it should and all hoses are getting warm so no problems there. I even squeezed the hell out of the 2 small ones at the back of the bay going into the heating system. All warm all in order.

    I then ran the fans etc, when I set the temp to 22 degrees the air goes very hot, then normal, then very hot, then normal. I'm sure I can hear something 'adjusting' behind the dash...right where all the heater system etc.

    I'm guessing its some sort of control thats f*cked, as you can hear it adjusting as the air gets very hot and then goes back down to normal. When the AC is set on 'lo' it stays cold which is good, but any temp above that is a nightmare. About every 5 seconds or so the air changes temp. So hot....cool...hot....cool....hot....cool and so on.

    Does anyone know of any causes to this or what I can look at to sort it out?. Its getting on my whick now in rather a large way. I looked in the Haynes book but because my car has climate it just says go to Audi :(

    Anyone shed some light?. Looking at how the system on non AC cars is removed its a HUUUUUUGE job to take the heating system out :(
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  10. MIKE GTR
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    MIKE GTR Member

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    [Mar 14, 2010]
    Perhaps its the thermostat on the control unit (i assume that they must have one to keep them at the set temp) - have you got a mate who will let you swap units over just to test
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  11. A3Tom
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    A3Tom Smell my finger.

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    [Mar 14, 2010]
    The thermostat on the unit is in the dash and thats fine I would imagine.

    I think its something 'mechanical' that mixes the air to the required temp...you can hear it whirring. From a bit of digging on the internet I think it can be checked via VAGCOM, anyone got any ideas?
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  12. Khufu
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    Khufu Well-Known Member

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    [Mar 14, 2010]
    You used to be able to get air con diagnostic codes from the control panel by pressing a combination of buttons. Sorry but I cant find them anymore.
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  13. A3Tom
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    A3Tom Smell my finger.

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    [Mar 14, 2010]
    Cheers mate, I think I've got them somewhere so I'll try and dig them out.

    Really dont fancy taking the dash out!
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  14. rossbrownlee
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    rossbrownlee Ross_S4

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    [Mar 14, 2010]
    Tom you can have the hvac scanned on vagcom, it is block 8 i think.
    that should tell you something.
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  15. sportstractor
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    sportstractor Chugger

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    [Mar 14, 2010]
    this is what you want

    http://www.audiforums.com/forum/archive/index.php/t-21703.html

    sounds to me like your interior sensor could be playing up.

    monitor this one 'Digital value of Interior Temperature Sensor, in Instrument Panel'

    and see whats its reading, this should change according to interior temperture. This is the place id look anyway

    This would have no connection to changing the stat i think, as it is only a heat matrix, and the system will completely bleed itself, unlike the old systems.
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  16. A3Tom
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    A3Tom Smell my finger.

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    [Mar 14, 2010]
    Cheers guys, I think I'll replace the in car thermostat as its not going to cost much...although I'm not convinced thats the issue.

    I just need to get someone near by with VAGCOM so I can see whats occuring before I rip the dash apart!.
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  17. sportstractor
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    sportstractor Chugger

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    [Mar 14, 2010]
    bit dissmissive mate, it has to be purely coensquence. I cant see how it could be related.

    Well the unit itself with give you fault codes, so no need for vagcom

    '1 System malfunction - displayed as a Diagnostic Trouble Code (DTC), see chart below'
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  18. rossbrownlee
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    rossbrownlee Ross_S4

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    [Mar 14, 2010]
    Because the hvac in there has various temperature sensors and motors in i would get it scanned before replacing anything imho.
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  19. Omniquito
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    Omniquito Member

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    [Nov 1, 2012]
    Hey A3Tom did you get this sorted mate? My S3 is doing the exact same after I replaced the stat and I can't figure it out :/
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  20. voorhees
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    voorhees Moderator Staff Member Moderator

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    [Nov 1, 2012]
    He hasn't been on for nearly a year so he may not reply.
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  21. comdw
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    comdw Member VCDS Map User

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    [Nov 2, 2012]
    I have this problem too on my S3. Started when the weather got cold, had nothing changed on the car around that time though. Set at 18 or above it continuously alternates between blowing hot and luke warm (which makes the car hot in the end). I'm switching between 18 and LO to control the temp! LO still blows cold only.
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