Low RPM Whine & AC

Jurisprudent · 10-03-2011, 05:38 PM

Guys, I've posted a clip of the sound below. It's not quite as low pitched/deep sounding as the recording (at least on my computer), but this was recorded with a BlackBerry, so you get what you get, I guess.

The blower was replaced a little over a year ago, so I have a hard time thinking it is that, again, but who knows. Perhaps a bearing or tensioner? This is recorded inside the car, crawling along in traffic in 1st gear. The car is a 6MT, to the extent that matters. The sound is somewhat intermittent, but it's becoming more consistent lately (don't know if that is temperature related or not).

http://k003.kiwi6.com/hotlink/lg65bt4o26/ac_sound.mp3

In case that doesn't work - there is a spot to play it here:

http://kiwi6.com/file/lg65bt4o26

Appreciate any help!

mike3000fl · 10-03-2011, 06:46 PM

does the whine change with the speed of the ac fan setting?

does it go away when the compressor is turned off?

Jurisprudent · 10-03-2011, 06:53 PM

Quote:

Originally Posted by mike3000fl

does the whine change with the speed of the ac fan setting?

does it go away when the compressor is turned off?

No, it doesn't change based on the speed. But, yes, if I turn off the compressor, it goes away completely. You can hear it in the sound clip if you turn it up loud enough... the whine does seem to change with revs, and at some point it either goes away or is simply drowned out by the rest of the engine/road noise.

I should add that I have 2 weeks of CPO warranty left. Lucky me, hopefully... Although if it is refrigerant or something like that I imagine it won't be covered.

Jurisprudent · 10-03-2011, 07:12 PM

March '05 build, by the way. She's been around for some time now

Jurisprudent · 10-04-2011, 08:26 PM

No idea Mike?

Patrick303 · 10-04-2011, 08:52 PM

In my experience, a low rpm whine noise has been due to a bad ground wire on your stereo.

mike3000fl · 10-04-2011, 08:53 PM

if it doesn't change with ac fan setting, then that makes me want to believe it is not the blower fan itself.

the fact it goes away with the ac compressor off means it is probably something like you mentioned on the accessory belt, could be the compressor itself or hopefully something less expensive such as a tensioner or bearing.

some of the e90's (especially after a new windshield) will leak water down the windshield cowling in front of the passenger. this collects in an area below the microfilter where the ac recirculate vent is (looks like slats and opens and closes based on ac recirc switch position). anyway this water makes its way down the vent and onto the blower motor, rusting the bearings and causing squeaking or squealing. often water collects on the passenger floor mat after heavy rain. this kind of noise changes with the ac fan setting so i am thinking it is not this, but feel around down there on the carpet after a hard rain to see if it feels moist.

CarguyBimmer · 10-04-2011, 09:03 PM

My car has a similar accessory noise (dependant with rpm) and dealer says i need a new power steering pump. The noise is there with or whitout a/c. That noise is there since i got the car brand new. I have an appointment this friday to have that pump changed. I'll let you know if it really was the pump.

CarguyBimmer · 10-08-2011, 07:31 AM

Power steering pump changed yesterday and whine is gone!

EQUANT · 10-10-2011, 03:29 PM

I have some sort of whine on my car as well when the AC is on and the outside temp is really really high. It goes away when turning AC off or rpm above 1500rpm.

mike3000fl · 10-10-2011, 03:31 PM

Quote:

Originally Posted by EQUANT

I have some sort of whine on my car as well when the AC is on and the outside temp is really really high. It goes away when turning AC off or rpm above 1500rpm.

yours might be the engine fan. normal, jet engine sounding?

EQUANT · 10-10-2011, 10:15 PM

No, not that. It's a small whine each time i accelerate the car slightly from idle. I think due to the very high temp, there is more stain on the AC compressor; might be a belt whine. It does not do it unless it's very hot, 35*C+

My previous car had the same symptoms, so i don't think it's an issue.

bluescoupe · 10-12-2011, 11:06 AM

Very interesting.

I have the same whine/drone, audible at low rpms (and speed).
And not all the time, usually after the engine has been running a while.
But turn off the compressor, and it goes away everytime.

Also, if I hit AC MAX for a little while, sometimes it doesn't come back for a while.

Curious isn't it?

RupertPupkin · 10-12-2011, 12:59 PM

in for the same thing as OP. AC on it whines, AC off it doesnt. Independent of stereo on/off. no water on floor, no water on blower. Only when the AC compressor is active.

in for solution.....

2006 330i 6MT

Jurisprudent · 10-13-2011, 11:45 AM

I was told by dealer that it is "normal". My CPO warranty is up in 4 days. Convenient, but hopefully they are right.

EDIT: To be fair, when I took it in, it was raining for the first time in weeks. The noise was still there but it did seem somewhat subdued. I don't know if the rain/moisture (or resulting lower temps) played a part in that or not. The last few days it has continued to be a little less noticeable... not sure what it is. They felt it was normal compressor noise.

10-03-2011, 05:38 PM	#1
Jurisprudent Second Lieutenant 21 Rep 226 Posts Drives: '15 335i M-Sport Join Date: Oct 2007 Location: Coastal SC iTrader: (0)	Low RPM Whine & AC Guys, I've posted a clip of the sound below. It's not quite as low pitched/deep sounding as the recording (at least on my computer), but this was recorded with a BlackBerry, so you get what you get, I guess. The blower was replaced a little over a year ago, so I have a hard time thinking it is that, again, but who knows. Perhaps a bearing or tensioner? This is recorded inside the car, crawling along in traffic in 1st gear. The car is a 6MT, to the extent that matters. The sound is somewhat intermittent, but it's becoming more consistent lately (don't know if that is temperature related or not). http://k003.kiwi6.com/hotlink/lg65bt4o26/ac_sound.mp3 In case that doesn't work - there is a spot to play it here: http://kiwi6.com/file/lg65bt4o26 Appreciate any help! __________________
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10-03-2011, 06:46 PM	#2
mike3000fl Banned 138 Rep 2,731 Posts Drives: 06 330i Join Date: Feb 2010 Location: Tampa iTrader: (0)	does the whine change with the speed of the ac fan setting? does it go away when the compressor is turned off?
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10-03-2011, 07:12 PM	#4
Jurisprudent Second Lieutenant 21 Rep 226 Posts Drives: '15 335i M-Sport Join Date: Oct 2007 Location: Coastal SC iTrader: (0)	March '05 build, by the way. She's been around for some time now __________________
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10-04-2011, 08:26 PM	#5
Jurisprudent Second Lieutenant 21 Rep 226 Posts Drives: '15 335i M-Sport Join Date: Oct 2007 Location: Coastal SC iTrader: (0)	No idea Mike? __________________
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10-04-2011, 08:52 PM	#6
Patrick303 Lieutenant 675 Rep 474 Posts Drives: F36 440i GC Join Date: Jan 2011 Location: Denver, CO iTrader: (2) Garage List 2017 Ducati Monster ... [0.00] 2017 BMW 440i xDriv ... [0.00]	In my experience, a low rpm whine noise has been due to a bad ground wire on your stereo. __________________ 2024 Porsche Taycan 4S 2017 Ducati Monster 821
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10-04-2011, 08:53 PM	#7
mike3000fl Banned 138 Rep 2,731 Posts Drives: 06 330i Join Date: Feb 2010 Location: Tampa iTrader: (0)	if it doesn't change with ac fan setting, then that makes me want to believe it is not the blower fan itself. the fact it goes away with the ac compressor off means it is probably something like you mentioned on the accessory belt, could be the compressor itself or hopefully something less expensive such as a tensioner or bearing. some of the e90's (especially after a new windshield) will leak water down the windshield cowling in front of the passenger. this collects in an area below the microfilter where the ac recirculate vent is (looks like slats and opens and closes based on ac recirc switch position). anyway this water makes its way down the vent and onto the blower motor, rusting the bearings and causing squeaking or squealing. often water collects on the passenger floor mat after heavy rain. this kind of noise changes with the ac fan setting so i am thinking it is not this, but feel around down there on the carpet after a hard rain to see if it feels moist.
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10-04-2011, 09:03 PM	#8
CarguyBimmer New Member 1 Rep 9 Posts Drives: 2011 E90 323i Join Date: Aug 2011 Location: Canada iTrader: (0)	My car has a similar accessory noise (dependant with rpm) and dealer says i need a new power steering pump. The noise is there with or whitout a/c. That noise is there since i got the car brand new. I have an appointment this friday to have that pump changed. I'll let you know if it really was the pump. __________________ Current fleet : 2011 E90 N52B25
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10-08-2011, 07:31 AM	#9
CarguyBimmer New Member 1 Rep 9 Posts Drives: 2011 E90 323i Join Date: Aug 2011 Location: Canada iTrader: (0)	Power steering pump changed yesterday and whine is gone! __________________ Current fleet : 2011 E90 N52B25
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10-10-2011, 03:29 PM	#10
EQUANT First Lieutenant 28 Rep 317 Posts Drives: 320d Join Date: Dec 2009 Location: Bucharest iTrader: (0)	I have some sort of whine on my car as well when the AC is on and the outside temp is really really high. It goes away when turning AC off or rpm above 1500rpm. __________________ BMW 320 dA LCI, BMW PPK - 197HP, 2010, sapphire black, steptronic
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10-10-2011, 10:15 PM	#12
EQUANT First Lieutenant 28 Rep 317 Posts Drives: 320d Join Date: Dec 2009 Location: Bucharest iTrader: (0)	No, not that. It's a small whine each time i accelerate the car slightly from idle. I think due to the very high temp, there is more stain on the AC compressor; might be a belt whine. It does not do it unless it's very hot, 35*C+ My previous car had the same symptoms, so i don't think it's an issue. __________________ BMW 320 dA LCI, BMW PPK - 197HP, 2010, sapphire black, steptronic
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10-12-2011, 11:06 AM	#13
bluescoupe motorhead 57 Rep 465 Posts Drives: 2017 M2 Join Date: Mar 2008 Location: west coast, FL iTrader: (0)	Very interesting. I have the same whine/drone, audible at low rpms (and speed). And not all the time, usually after the engine has been running a while. But turn off the compressor, and it goes away everytime. Also, if I hit AC MAX for a little while, sometimes it doesn't come back for a while. Curious isn't it?
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10-12-2011, 12:59 PM	#14
RupertPupkin Major 92 Rep 1,456 Posts Drives: Freak Beast Join Date: Aug 2011 Location: East iTrader: (5)	in for the same thing as OP. AC on it whines, AC off it doesnt. Independent of stereo on/off. no water on floor, no water on blower. Only when the AC compressor is active. in for solution..... 2006 330i 6MT
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10-13-2011, 11:45 AM	#15
Jurisprudent Second Lieutenant 21 Rep 226 Posts Drives: '15 335i M-Sport Join Date: Oct 2007 Location: Coastal SC iTrader: (0)	I was told by dealer that it is "normal". My CPO warranty is up in 4 days. Convenient, but hopefully they are right. EDIT: To be fair, when I took it in, it was raining for the first time in weeks. The noise was still there but it did seem somewhat subdued. I don't know if the rain/moisture (or resulting lower temps) played a part in that or not. The last few days it has continued to be a little less noticeable... not sure what it is. They felt it was normal compressor noise. __________________
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