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Hissing A4

Discussion in 'A4/S4 forum(B5 Chassis)' started by AndyMac, Jul 14, 2003.

  1. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 14, 2003]
    I've seen some posts about hissing. My A4 2.8Q has always hissed for a few minutes when you turn off the engine. I recently had to have the AirCon compressor & dryer replaced as it had been slowly leaking since I've had the car and no one could locate the leak (Audi are useless on AirCon, £90 a time for re-gassing). I thought the hissing might stop once I'd spent £600 on the ungrateful AirCon system, but it's still there.
    Any ideas? Or is this normal. It does actually sound quite good, like it is slowly relaxing after a good thrashing, but it can't be right can it?
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  3. mramage
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    mramage Member

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    [Jul 14, 2003]

    Hi Andy. Hissing is normal. All the cars I've had with aircon hiss to some extent. My A4 did.

    /ubbthreads/images/graemlins/beerchug.gif
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  4. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 14, 2003]
    Cheers Mark, wifey's A3 1.8TS doesn't hiss at all though, wierd.
    #3
  5. excursion
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    excursion Member

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    [Jul 14, 2003]
    Have a TDI B5 A4 here - 26,000 miles and it too does this. Has done since had the car at 8,000 miles - perfectly normal it seems /ubbthreads/images/graemlins/smile.gif
    #4
  6. JohnH
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    JohnH Member

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    [Jul 14, 2003]
    Mine hisses too, was gonna get it checked out, but may not bother now as a few of us seem to have the same thing.

    Regards,

    John
    #5
  7. Patrick
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    Patrick Member

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    [Jul 15, 2003]
    My 97 S4 (2.7) hisses has done since 34K miles and still does at 56K miles.

    I assume ok.
    #6
  8. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Jul 15, 2003]
    Well I'm glad I'm in such good company. Thought the old girl (112k miles), was getting out of breath. Thanks for all the reassurance. Cheers, Andy
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  9. Fraser
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    Fraser Member

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    [Apr 5, 2004]
    mine is hissing more than usual, just had the aircon redone after not using it all winter... no leaks as the guy checked all hoses and the pumps plus the condenser was ok... so guess all is normal..

    just need to use the aircon more ! /ubbthreads/images/graemlins/cool.gif
    #8
  10. jdp1962
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    jdp1962 Grumpy Old Moderator Staff Member Moderator

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    [Apr 5, 2004]
    [ QUOTE ]
    Fraser said:
    mine is hissing more than usual, just had the aircon redone after not using it all winter... no leaks as the guy checked all hoses and the pumps plus the condenser was ok... so guess all is normal..

    just need to use the aircon more ! /ubbthreads/images/graemlins/cool.gif

    [/ QUOTE ]
    I'm about to get my climate control serviced. Should I use an Audi dealer, or an independent air-con specialist?
    #9
  11. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 5, 2004]
    Jeff, I'd use an aircon specialist. (unless you're still under warranty)
    Southampton Audi didn't really have a clue with my leak, they just regassed it (£98 thankyou), then regassed it again a few weeks later with a dye in it (£98 thankyou), then said they couldn't find a leak.
    Took it to a specialist, who had to regas (again), but at least it was only £68 (obviously didn't use the highly refined Audi branded Freon).
    The specialist found the leak immediately, but unfortunately it needed a new dryer.
    To be fair it's not really Audi's bag, like tyres or exhausts, so why pay £70+ an hour for something they're not very good at?
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  12. jdp1962
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    jdp1962 Grumpy Old Moderator Staff Member Moderator

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    [Apr 5, 2004]
    [ QUOTE ]
    AndyMac said:
    Jeff, I'd use an aircon specialist. (unless you're still under warranty)
    Southampton Audi didn't really have a clue with my leak, they just regassed it (£98 thankyou), then regassed it again a few weeks later with a dye in it (£98 thankyou), then said they couldn't find a leak.
    Took it to a specialist, who had to regas (again), but at least it was only £68 (obviously didn't use the highly refined Audi branded Freon).
    The specialist found the leak immediately, but unfortunately it needed a new dryer.
    To be fair it's not really Audi's bag, like tyres or exhausts, so why pay £70+ an hour for something they're not very good at?

    [/ QUOTE ]

    Cheers, Andy. I've just been doing some browsing in the meatime, & came across this website. It's given me quite a few tips on the system, plus recommernded some firms in my local area to contact. Oh, & by the way, the weather was pretty warm last week when I was driving back to London from Manchester, & when I got out of the car, it hissed for the first time this year /ubbthreads/images/graemlins/smile.gif

    http://www.autoclimate.com/
    #11
  13. excursion
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    excursion Member

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    [Apr 5, 2004]
    Summers coming, summers coming, whoo whoo!!! /ubbthreads/images/graemlins/laugh.gif /ubbthreads/images/graemlins/grin.gif
    /ubbthreads/images/graemlins/groovy.gif

    (all 2 weeks of it)
    #12
  14. Fraser
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    Fraser Member

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    [Apr 5, 2004]
    I use a specialist, guy does jags and audi's £50 for the regas, guy also did a suspension arm and was kind enough to show me how it was done whilst it was on the ramp... /ubbthreads/images/graemlins/smile.gif

    Yeah summer on the way, noticed the aircon wasn't cold when it was hot last week, now it ios all rainy and the aircon is working fine /ubbthreads/images/graemlins/wink.gif
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  15. mastertech
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    mastertech Member

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    [Apr 5, 2004]
    the hissing noise you hear is the air con equalising pressure.the system has a low pressure side and a high pressure side when the compressor is running.when the engine or compressor is turned off the high pressure is bled off through the restrictor causing the noise you hear.
    #14
  16. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 5, 2004]
    But since I had it fixed it doesn't hiss anymore, not noticeably anyway
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  17. mastertech
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    mastertech Member

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    [Apr 5, 2004]
    with the correct fill of gas the noise is reduced.
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  18. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 6, 2004]
    But it was still hissing after each regas.
    When I had the new dryer fitted (which was leaking) the hissing stopped.
    #17
  19. Mutinyno9
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    Mutinyno9 Member

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    [Apr 6, 2004]
    I have a 99 A4 1.8 and mine doesn't hiss at all, i rarely ever use the ECON air and usually have it on fulltime aircon, yet still mine doesn't hiss after the car is turned off.
    #18
  20. jdp1962
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    jdp1962 Grumpy Old Moderator Staff Member Moderator

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    [Apr 16, 2004]
    [ QUOTE ]
    AndyMac said:
    Jeff, I'd use an aircon specialist. (unless you're still under warranty)
    Southampton Audi didn't really have a clue with my leak, they just regassed it (£98 thankyou), then regassed it again a few weeks later with a dye in it (£98 thankyou), then said they couldn't find a leak.
    Took it to a specialist, who had to regas (again), but at least it was only £68 (obviously didn't use the highly refined Audi branded Freon).
    The specialist found the leak immediately, but unfortunately it needed a new dryer.
    To be fair it's not really Audi's bag, like tyres or exhausts, so why pay £70+ an hour for something they're not very good at?

    [/ QUOTE ]

    It's going in tomorrow for an air-con service. I'm using a local specialist that I found on a website called www.automclimate.com. They will do a free check first, then a service if it's needed (no doubt it will be!), which costs £85 plus VAT. I'lle let you know how it gets on.
    #19
  21. jdp1962
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    jdp1962 Grumpy Old Moderator Staff Member Moderator

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    [Apr 17, 2004]
    All sorted today. Had a full health-check done, & it only had 520g of gas in it, instead of the 750g it's meant to have. I suspect that's the first service & re-charge it's ever had in the five years since it was first bought (I've had it a year). Certainly, there was no evidence any leaks (that he could find). I suspect if it had a leak, it would have lost more gas more quickly.
    Anyway, it's now fully re-charged with non-toxic mineral-based gas (R134, I think it's called), and has been treated with anti-bacterial stuff, so hopefully, I won't catch legionnaire's disease, heheheh! Cost was £100.

    I wonder if it'll still hiss...
    #20
  22. jdp1962
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    jdp1962 Grumpy Old Moderator Staff Member Moderator

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    [May 7, 2004]
    [ QUOTE ]
    excursion said:
    Summers coming, summers coming, whoo whoo!!! /ubbthreads/images/graemlins/laugh.gif /ubbthreads/images/graemlins/grin.gif
    /ubbthreads/images/graemlins/groovy.gif

    (all 2 weeks of it)


    [/ QUOTE ]

    Two weeks? Ha! We've just had three months' rainfall in the last two bloody weeks.

    (BTW, no hissing)
    #21
  23. mrg
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    mrg New Member

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    [May 15, 2004]
    My 2.4 avant 99 has always hissed, 1yr and 6mths owned, 58K to 86K.
    MRG
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