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Thread: Hissing A4

  1. #1
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    Hissing A4

    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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    Re: Hissing A4


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

    [img]/ubbthreads/images/graemlins/beerchug.gif[/img]

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    Re: Hissing A4

    Cheers Mark, wifey's A3 1.8TS doesn't hiss at all though, wierd.

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    Re: Hissing A4

    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 [img]/ubbthreads/images/graemlins/smile.gif[/img]

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    Re: Hissing A4

    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

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    Re: Hissing A4

    My 97 S4 (2.7) hisses has done since 34K miles and still does at 56K miles.

    I assume ok.

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    Re: Hissing A4

    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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    Re: Hissing A4

    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 ! [img]/ubbthreads/images/graemlins/cool.gif[/img]

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    Re: Hissing A4

    [ 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 ! [img]/ubbthreads/images/graemlins/cool.gif[/img]

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

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    Re: Hissing A4

    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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    Re: Hissing A4

    [ 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 [img]/ubbthreads/images/graemlins/smile.gif[/img]

    http://www.autoclimate.com/

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    Re: Hissing A4

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

    (all 2 weeks of it)

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    Re: Hissing A4

    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... [img]/ubbthreads/images/graemlins/smile.gif[/img]

    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 [img]/ubbthreads/images/graemlins/wink.gif[/img]

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    Re: Hissing A4

    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.

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    Re: Hissing A4

    But since I had it fixed it doesn't hiss anymore, not noticeably anyway

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    Re: Hissing A4

    with the correct fill of gas the noise is reduced.

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    Re: Hissing A4

    But it was still hissing after each regas.
    When I had the new dryer fitted (which was leaking) the hissing stopped.

  19. #18
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    Re: Hissing A4

    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.

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    Re: Hissing A4

    [ 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.

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    Re: Hissing A4

    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...

  22. #21
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    Re: Hissing A4

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

    (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)

  23. #22
    mrg
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    Re: Hissing A4

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

 

 

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