A/C system delivers the desire temperature but noisy

Tiny
MIKEPAP39
  • MEMBER
  • 1999 BMW 520
  • 2.0L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 106,000 MILES
It has been sometime now that despite season (meaning that the problem appears both summer and winter) the system delivers the desire temperature but noisy. The noise is not metal or cranky but kind of when somebody is trying to blow as much stronger as he can. This annoying situation exists from the first scale of blow power.
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Thursday, February 21st, 2019 AT 11:43 PM

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Tiny
STEVE W.
  • MECHANIC
  • 12,788 POSTS
Does the noise get louder as the fan speed increases? If so it is likely to be the blower motor, either worn bearings or something in the squirrel cage that is making it go out of balance.
Anther possibility is that one of the ducts connected to the HVAC case has come partly off and what you are hearing is an air leak, that may not get louder as the fan speed increases, depending on where it is.
I would check the ducting first, there are ducts under the seats and inside the center console to feed those. If something was under the seat it could be blocking a duct. Not uncommon.
For the blower motor the HVAC unit has to be removed, that requires the seats, steering column and dash assembly be removed to get in there.
You might also want to see if the cabin filter is clean and installed correctly, that could be partly blocked or loose and letting air pass around it.
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Friday, February 22nd, 2019 AT 7:09 AM

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