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Thread: New front FSU in order for car? 2003 E39 530i

  1. #1
    Join Date
    Mar 2010
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    SF Bay Area, CA
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    118
    My Cars
    2003 BMW 530i (Auto)

    New front FSU in order for HVAC blower? 2003 E39 530i

    We've had the car for just shy of a month, 166,xxx miles, and my first BMW. Automatic/Thermostatically controlled dual-zone HVAC system.

    This new-to-us car has, since we bought it, tended to have a midrange-pitched "rrrrr" sound that seems to increase or decrease with Engine RPM's when you're using lower blower speeds where you can hear it do so. You can clearly hear it with the car idling while seated in the interior, and cruising at low speeds in town.

    When I found in the Owner's Manual how to shut the HVAC system off completely, suddenly the "rrrrrrrr" sound went away too. Virtually as silent as the inside of a bank vault. Now mind you, at-speed the sound is very minimal and doesn't increase with blower speeds which, BTW, all blower speeds function normally and without any overt and unusual noise; and all HVAC functions appear to work flawlessly. It's simply in-town driving that this a nuisance to an otherwise very, VERY quiet car...and is engine RPM related (alternator speed?). The sound seem to be coming from the front/dash.

    This sound in question does NOT increase with higher blower speeds.

    If my description is easy to understand, is this sound normal for these cars, or is it the early stage of a failing FSU? I see it's a fairly simple DIY replacement part, and I'd rather replace it before I lose blower speeds or the battery gets drained.

    Thank you so much.
    Last edited by 1BlinkGone; 03-25-2019 at 04:28 AM.

  2. #2
    Join Date
    Oct 2017
    Location
    Beaverton, Oregon, USA
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    1,694
    My Cars
    2001 E39 540i A, 207 k
    My guess it is the alternator....

  3. #3
    Join Date
    Jun 2015
    Location
    Sydney, NSW, Australia
    Posts
    231
    My Cars
    1999 E39 M5
    Have a read of the first post of this:-

    https://www.bimmerfest.com/forums/sh.../422191?page=5

    Then skip to post 45 for the fix.

    (You don’t need to remove the radio/OBM to remove the IHKA unit - just use plastic trim tools to lever it out)

  4. #4
    Join Date
    Mar 2010
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    SF Bay Area, CA
    Posts
    118
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    2003 BMW 530i (Auto)
    Quote Originally Posted by RosieE39 View Post
    Have a read of the first post of this:-

    https://www.bimmerfest.com/forums/sh.../422191?page=5

    Then skip to post 45 for the fix.

    (You don’t need to remove the radio/OBM to remove the IHKA unit - just use plastic trim tools to lever it out)
    YES!!! This is exactly what it sounds like....a like a computer fan noise from behind that HVAC (IHKA) panel!! You are a gentleman and a scholar and I thank you!

  5. #5
    Join Date
    Aug 2010
    Location
    Oregon
    Posts
    1,269
    My Cars
    '99 528i/5, '01 Boobaru
    Quote Originally Posted by 1BlinkGone View Post
    YES!!! This is exactly what it sounds like....a like a computer fan noise from behind that HVAC (IHKA) panel!! You are a gentleman and a scholar and I thank you!
    If cleaning the IHKA sampling fan works, that will be great, but the system blower fan itself can also be the source and it's a bit more trouble (and $) to replace. I've noticed the rpm-dependent whine only when I have the AC on. Was told by one mechanic to have the AC refrigerant recharged first and see if that halted it. So far just living with it as I only use the AC a couple weeks out of the year.

  6. #6
    Join Date
    Mar 2010
    Location
    SF Bay Area, CA
    Posts
    118
    My Cars
    2003 BMW 530i (Auto)
    Quote Originally Posted by pleiades View Post
    If cleaning the IHKA sampling fan works, that will be great, but the system blower fan itself can also be the source and it's a bit more trouble (and $) to replace. I've noticed the rpm-dependent whine only when I have the AC on. Was told by one mechanic to have the AC refrigerant recharged first and see if that halted it. So far just living with it as I only use the AC a couple weeks out of the year.
    Thank you for your post and I understand what you are saying. With that, the sound I'm hearing has nothing to do with the blower itself, or its speed. Best as I can tell - that sound is originating from behind the HVAC panel, and isn't in sync with the blower speed at all. Thanks again!! This is a fantastic forum and thank you all.
    Last edited by 1BlinkGone; 03-27-2019 at 12:25 AM.

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