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Hot air smell

Discussion in 'A3/S3 Forum (8L Chassis)' started by metricspaces, Oct 7, 2013.

  1. metricspaces
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    metricspaces Member

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    [Oct 7, 2013]
    Hi folks, just wondering if any has any ideas of what my problem could be here.

    I've an Audi S3 1999 and when I turned on the hot air there were strong fumes coming out.

    After reading up on the forum, the most likely problem seemed to be the heater matrix. I replaced this. It was leaking coolant

    Now, there is still fumes there when you turn on the hot air. It seems to be more noticeable for the first few seconds when you turn it on (but that could just be because you get used to it after that). What could be causing this?

    My understanding of the set up is that the hot\cold air comes from the same input point. The only difference is when you turn on the hot air it gets redirected to pass over the heater matrix.

    Any ideas or suggestions appreciated :)
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  3. s3dave
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    s3dave TFSI Hybrid Supporter

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    [Oct 7, 2013]
    It may want the air con disinfecting, halfords etc do a cleaning bomb that are effective ..
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  4. [Dave B]
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    [Dave B] Daddy

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    [Oct 7, 2013]
    Might be worth changing the cabin filter too for good measure.
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  5. JohnnyM100
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    JohnnyM100 Active Member

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    [Oct 7, 2013]
    +1
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  6. metricspaces
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    metricspaces Member

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    [Oct 7, 2013]
    Sounds like a good idea! I've no idea what the internals of the air con system look like...i.e. is there much of a separate area that the air gets directed over the heater matrix for coolant to been left even after changing the matrix.

    Not sure about cabin filter. Is the cabin filter not at a point in the system after the air has gone directly through (cold air) or diverted over heater matrix (hot air). If this is the set up, the both hot and cold air are going through the filter. As I'm not getting any fumes\smell on cold hair, then guessing the filter is good?

    Or maybe the fumes could be coming from the filter, but only when it gets heated up with hot air and not obvious on cold air?
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  7. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Oct 7, 2013]
    Heater matrix is a beast of a job. Entire dash board out! I've done it and it's not fun.
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  8. metricspaces
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    metricspaces Member

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    [Oct 7, 2013]

    Ya, matrix is replaced. But there's still fumes there - just not as strong as before.

    Regards cleaning the area around the heater matrix...would this be the entire dash board out again? Or it would be possible to get enough access to clean the area?
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  9. metricspaces
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    metricspaces Member

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    [Oct 7, 2013]
    Did a search on Halfords there. This is the only one that shows up Halfords | Comma Aircon Cleaner

    The review of it here doesn't sound like it's that useful. Apparently you spray it into the cabin and let it circulate through the system. Can't see how that would give the internals much of a cleaning Evilution - Smart Car Encyclopaedia

    Anyone know any other good products?
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  10. metricspaces
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    metricspaces Member

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    [Oct 7, 2013]
    I checked it there again. Definitely only happens when the hot air is on.

    Turned on cold air. No smell.
    Turned on hot air. Immediately get smell.
    Turned back to cold air. Smell immediately goes away.
    Turned on hot air. Immediately get smell.

    So definitely only coming from the area where the hot air goes through.

    Does this rule out the filter?
    Would those Aircon cleaners be any good for this?
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  11. metricspaces
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    metricspaces Member

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    [Oct 7, 2013]
    [​IMG]

    Just took a look at VAGCAT there. If I'm reading this diagram right, then...

    - The input is where I have the blue arrow at the top, where the filter is
    - When the air reaches the orange diamond I have drawn then it goes straight out if cold air is on
    - When the air reaches the orange diamond and hot air is on, then the air is directed over the heater matrix (part # 30)

    So from looking at this diagram, there is a very small area for this problem to *only* be occurring when the hot air is on i.e. the part of the main body of the air unit that holds the heater matrix.

    Sound right?

    Attached Files:

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  12. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Oct 8, 2013]
    Sounds exactly the same as when my matrix went. Be very annoying for you if it's where some coolant leaked into the casing around the matrix that you hadn't noticed when you fitted a new one.
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  13. metricspaces
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    metricspaces Member

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    [Oct 8, 2013]
    Darn. Sounds like the only way to fix this is pull it all out again and clean the section that the heater matrix slots into?
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  14. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Oct 8, 2013]
    Unfortunately that's the only way to investigate the matrix. I feel your pain mate I really do.
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