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3.0 tdi CDUC ( AC possible problem )

Leighspain1975 Jun 29, 2020

  1. Leighspain1975

    Leighspain1975 Member

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    Hi

    just a quick question. Could a faulty ac compressor cause enough problems on engine load that you would notice slight power loss or like the engine is dragging something?.

    also Can faulty AC cause a rattle only under load but not necessarily during idle ?.

    many thanks
     
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  3. Mo-S3

    Mo-S3 Active Member

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    What makes you think its the ac compressor? does it still work?
     
  4. Leighspain1975

    Leighspain1975 Member

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    It’s really strange.

    at first I thought it was an injector problem. It sounds like a proper diésel clatter noise when accelerating and I noticed it was very intermittent.
    If I switched off the Ac and put the temp to high for 5-10 mins the noise would suddenly disappear.
    With the AC on I can hear a kind of injector pinging noise that I thought was the injectors only to find it comes and goes when the AC is toggled on and off.

    I have also just measured engine load while at Idle

    15% Ac off
    35% Ac On

    don’t know if these numbers seem excessive with the AC on ?.

    thanks
     
  5. Mo-S3

    Mo-S3 Active Member

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    Have you looked at the aux belt and the ac pulley with the engine running? does it seem stable? not wobbling etc?
    I would start by removing the aux belt that drives all the front pulleys and see what the car sounds like. Take it for a very very short drive and see if makes the noise or not? Dont drive it long at all as the battery wont charge and you will break down. Bearing could be broken on the ac pump pulley?
     
  6. Leighspain1975

    Leighspain1975 Member

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    Many thanks for the reply.

    I can’t see any wobbles and the belt seems firmly in one place and not jumping around at all.
    But your right I need to take the belt off and test the car for rattles.
    It’s definitely only happening when the AC is On.
    If I leave the engine running with the Ac off and the heater on High it will make less rattle.
    Sound is very similar to injector pinging similar to when the car is in too low gear and you floor the gas and you get the pinging noise.
     

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