A/C Noise Help Pls!!

Discussion in '3 Series' started by bmwzoom, Mar 22, 2020.

  1. bmwzoom
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    bmwzoom

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    So even after the re gas I still have the whining noise that goes with the revs up until 1700 when the road noise then covers it, however turning off the A/C stops it??

    The noise seems to be coming from inside the car in the dash area to the right, does anyone know exactly what the A/C button controls?? As the compressor is clutched all the time so runs constantly, its as if the A/C button is controlling a separate fan of perhaps a valve or vent control & therefore letting the sound in from the engine bay maybe? Running in eco pro mode also reduces the sound to almost zero as does turning off the blower completely.

    Checked realoem and can't see anything in the diagrams. When googled seems to come up a lot as a common issue but no fix. Mine just appeared from nowhere after the egr cooler and idrive unit were replaced at a dealers.

    Any help or idea would be gratefully received trying to book back in with dealer but can't see that happening at the moment.

    Really really could use some input regardless of how strange it may sound.

    Thanks

    Pete
     
  2. slim_boy_fat
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    slim_boy_fat WARLORD Site Supporter

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    Fan bearing?
     
  3. bmwzoom
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  4. markyboyt
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    What about the expansion valve through the bulk head? Might worth listening to to that if you can get the noise while free revving
     
  5. bmwzoom
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    How do I get to it pls??
     
  6. bmwzoom
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    Noise definitely seems to be coming from inside the dash area around or behind the speedo to the right. Nothing much under the bonnet
     
  7. markyboyt
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  8. bmwzoom
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    Got it thanks but why would this cause a noise that tracks with the revs?? The sound is like a small fan speeding up and slowing down :whistle:. It goes on and off immediately with the A/C switch light a light would. Is there anything behind the dash as mine had a new Idrive unit + egr cooler replaced and then noise appeared after that work :mad:. A/C System is working fine and ice cold.

    Help pls driving me nuts:banghead: not going to BMW until may due to the current issues:( and I' am a key worker driving:driving: 100 miles a day!!
     
  9. markyboyt
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    The has passed through the expansion valve to and from the evaporator and obviously is driven by the engine. It’s not a guarantee but they can cause noise and it shouldn’t be too difficult to listen to with a stethoscope or screwdriver.
    In one of your old posts you said it was still there when you drive to work with the ac off?
     
  10. bmwzoom
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    Good morning,

    Quick update:

    Noise is only there when A/C is on when off car is quiet (sorry my hearing!) also when car is in eco mode I can't hear it either. Noise can be turned on and off via the A/C button and is immediate like turning a light on & off, noise also stops if you turn the blower off which shuts down all the heating etc, however blower alone is quiet. Noise is only present when engine is running & A/C on, leave A/C on and just the ignition (dash lights etc) no noise. Noise can only be heard inside the car inside the dash above / behind speedo not outside or under the bonnet at idle, noise is a little move prominent when driving (I think). A quick google proves that this is a common problem on 1,2,3,4 & 5 series that nobody including dealers seem to be able to fix:(. As already stated noise goes up and down with the rev range until 2k where engine noise and road noise mask it I presume:rolleyes:

    I am running out of idea's BMW want £99 to try and diagnose it then I have £250 excess on my warranty but no hope of a fix judging by online reports. Noise seems to have arrived after a visit to bmw for a new idrive unit and egr cooler replacement. A/C is fully charged and freezing cold and has been all along despite a service done 2 weeks ago.

    HELP :confusedmore::confusedmore::confusedmore::confusedmore:
     
  11. markyboyt
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    If its definitely within the dash then it might be time to start taking it apart, id have the head unit out seeing as its started since that was replaced, screen and instrument cluster out. Does the noise reproduce just free revving or do you need to be driving?
     
  12. bmwzoom
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    You need to be driving really although it is there slightly at free revving. I was thinking electrical or the A/C controller mounted behind the dash but these would be on with just ignition and all is quiet as is the idrive. The engine has to be running which makes no sense with electrical stuff behind the dash really. Looking on realoem other than the a/c controller it's all a bit bare. For it to track the revs it must be linked to a running engine
     
  13. bmwzoom
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    Thought about the rev counter being the issue but can't be as you can control the noise with the A/C switch
     
  14. kleynie
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    kleynie WARLORD Site Supporter

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    Had the same issue on my old E61, drove me nuts and I just learned to ignore it in the end. I think the expansion valve is a good shout though.
     
  15. bmwzoom
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    Is the valve electrically controlled? Still can't find it under the bonnet ?? Have seen it on realoem but can't place it under the bonnet:rolleyes: Any direction would be very helpful pls
     
  16. markyboyt
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    Follow the Air con pipes to the bulk head, this pic is LHD so ignore the steering column but it should be somewhere near. [​IMG]
     
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  17. xyzl
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    Just wondering what build date (month and year) applies to your F34?
     
  18. bmwzoom
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  19. bmwzoom
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    Found it! The picture was a great help thank you Passenger side so it is sprung loaded? Perhaps a gentle tap with a hammer in case its stuck half open maybe? What do you think???? Otherwise change it but it will need a re gas afterwards tho:(
     
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  20. xyzl
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    • Informative Informative x 2

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