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Aircon Issues.....?

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by djl78, Apr 4, 2008.

  1. djl78

    djl78 New Member

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    Having problems with the Aircon on my Allroad.Press the auto button and everything fires up as normal but temp doesn't drop.(fans runs ok)
    I was under the impression that if refrigerant was low the the auto light wouldn't come on.
    Anybody have any ideas or info beefore i take it to a garage to get ripped off?

    Thanks
     
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  3. maxlbrown

    maxlbrown Deep Blue

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    If you shop around you can get the System regassed and oiled for between 40- 50 quid which is a better bet than the cans from halfords (they charge 30 quid or so where in the states there between 4 and 8 dollors) unless you got a gauge already as it is easy to over fill and blow either a pipe or the compressor.

    I dont know where you are but here in reading and basingstoke we have few around who do this.

    M
     
  4. djl78

    djl78 New Member

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    Update...
    Took car to a friends garage and refrigerant was low (about half full) so had it charged up to correct amount.Aircon still not working though.Compressor clutch doesn't seem to kick in when Auto selected.Compressor doesn't appeare to be seized as it can the pulley can be moved by hand.Everything else seems ok.
    Anybody have any clues?????
    Could it be the safety switch that isn't working?
    Thanks:unsure:
     
  5. maxlbrown

    maxlbrown Deep Blue

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    sounds like a new compressor as if i remeber rightly the clutch is not replaceable on its own. there is a shear pin in the clutch so if the refridgerant is to high it prevents damage to the system and compressor. check out if the clutch is a replaceable part. but i am sure i have seen this elsewhere and clutch is an integral part to the compressor.

    M
     
  6. simonwjones

    simonwjones Member

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    definately the shear pin gone, you cant get the parts seprately and a new compressor is needed.

    They arent cheap and there are a few different models used so you need to get the right part number.

    Have a look on ebay for refurbed

    Simon
     
  7. djl78

    djl78 New Member

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    Managed to fix Air Con a couple of days after my last post.Basically found a loose connector between the magnetic clutch relay and the clutch itself.Reconnected and hey presto:yahoo:......ice cold air.
    Thankfully it was something simple that just needed a little fault diagnosis.
    Thanks for the input guys
     
  8. Staz

    Staz is a retronaut
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    Were you suggesting that you buy a can of R134a from Halfords and fill up the system youself using a pressure gauge??


    Glad you got it sorted. By the way the pressure being too low wouldn't cause the shear pin to fail. In fact if the pressure was too high the high pressure cut out would prevent damamge to the compressor unless the HPO failed.
     
  9. enda1

    enda1 Member

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  10. Staz

    Staz is a retronaut
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  11. maxlbrown

    maxlbrown Deep Blue

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    Yes you can get these through halfords. the kits have been available in the states for years and cost a tenth what they do here

    Out there you can get R134A and R12- R134a converstion kits and the new refrigerant

    this company also do some kits a lot cheaper. as long as you get the one with gauges there ok for a top off.
    http://www.coolcaraircon.co.uk/

    They are far from a waste of money i have used a number of these kits purchased both here and in the states from a full refill on a r12 to r134a converstion of a honda accord to a top up of my system. the refrigerant with oil in the states is about 4 bucks a can of 600mil most cars need no more than 1-1.200 grammes of refridgerant any way.

    I have the gauges and thermometers etc for this my point being why pay uk prices for these kits when you can get a full system check for the same money

    aircon recharging is getting very cheap now as more cars have aircon fitted.

    M
     
  12. enda1

    enda1 Member

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    Why is it stupid and why is it dangerous? How do you think they do it "professionally" they transfer the gas from one pressurised container to another ie from their cylinders to your car.
     
  13. Staz

    Staz is a retronaut
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    By the use of professional equipment. If you thing that sticking a hose on from a can is the same then you need to do some research, I'm not going to sit here and teach you.

    A starter for ten for you though, you cannot measure the amount of refrigerant in a system by its pressure. Anyone that claims to be able to do so doesn't know what they're talking about and has no concept of thermodynamics.

    Also they have the added bonus of being legally qualified to carry out work on ECS. Something which is pretty important in my eyes and is there for a reason.
     
  14. enda1

    enda1 Member

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    Well as a chartered engineer who studied thermodynamics at uni for 3 years I would like to point you in the direction of the equation below

    The state of an amount of gas is determined by its pressure, volume, and temperature according to the equation:
    PV=nRT
    where P
    is the absolute pressure of the gas, V is the volume of the gas, n is the number of moles of gas, R is the universal gas constant, T is the absolute temperature.
    P is known from the gauge, V is the volume of the sytem R is a constant and T is the ambient temperature and these will give you n the number of moles of the gas present and this equates directly into the mass of the gas
     
  15. Staz

    Staz is a retronaut
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    :applaus:

    The problem is, not all the refrigerant in the system is a gas. So, you cannot measure the weight of refrigerant in a system by its pressure.
     

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