I need help identifying a sound

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

DeltaT

DeltaT

10 Year
Joined
Jan 5, 2012
Threads
27
Messages
463
Location
Marlbank, ON
When my LX is cold (especially in the winter) there is a strange sound coming from behind the dash. It totally disappears when the vehicle heats up.
It sound a bit like a (dirty) electric fan. It seems that the pitch and volume changes when accelerating.
I have no idea what it is. Maybe you guys can help me out. I don't think it is related to the heater fan because it's not on when it's cold out and when it kicks in you can still hear the 'cricket's the background. So it's not freewheeling when the heater is off.

I made a sound clip this morning It was 12F out.

Chirp!

You can hear the chirping noise after about 1:20 minutes.

Any ideas before I start opening up the dash?
 
By "heater fan" are you referring to the blower motor that runs the a/c and heater? Sure sounds just like what you mentioned...a dirty blower fan. But if the heater and a/c are completely off, maybe not. If you are certain it's coming from the dash I would start by dropping the glove box just to double check the blower fan. If memory serves me right you can get close to it without actually pulling the motor. Just pop the plug off where some models have a cabin filter.
I would also check the clutch fan just to be sure there are no obvious obstructions, sounds a lot like a leaf or stick in a fan blade to me. Hope you track it down!
 
Thanks, yes, with heater fan I meant to say blower motor.
And I am not certain that the sounds originates from somewhere in the dash, but it seems that way.
What also puzzles me that it only happens when it is cold. As soon as that cabin heats up the sound is gone. And I can't remember hearing this noise last summer.
 
Weird. It has to be something spinning/moving like a fan or bearing on a drive belt pully. Good luck, let us know what you find.
 
Sure sounds like dry bearings on the heater blower motor. That would tend to go away as it warmed up. It may vary in speed with the engine because the blower motor would get more juice as the alternator runs faster. And, the blower motor does run at least a little all the time on my '04, though before the coolant heats up it runs at a very slow speed. I suggest pulling the blower motor (very easy to do under the right dash) and seeing if the squirrel cage fan runs smooth. I'll bet it doesn't.
 
Sandroad said:
Sure sounds like dry bearings on the heater blower motor. That would tend to go away as it warmed up. It may vary in speed with the engine because the blower motor would get more juice as the alternator runs faster. And, the blower motor does run at least a little all the time on my '04, though before the coolant heats up it runs at a very slow speed. I suggest pulling the blower motor (very easy to do under the right dash) and seeing if the squirrel cage fan runs smooth. I'll bet it doesn't.
Click to expand...

+1.......
 
I finally got the chance to take out the blower motor in the cold and took it for a drive while dangling. I am convinced now that it is not the blower motor.
If I turn the climate controls off, the blower motor stops turning but the chirp is still there.
It seems that I can manipulate the volume of the sound with my gas pedal and the tone goes up when I speed up, just as if the outside wind speeds up whatever makes the noise.
It is almost as if the sound originates from some kind of vacuum operated fan.

Weird or what ??

Virtual :beer: for the person that points me in the right direction.
 
The sound is still haunting me. Yesterday I got the chance to take another look. I took the nav screen and radio out, removed the blower motor, removed the interior filters en took a good look, but I still can't pinpoint the source. I even took it for a drive with all the stuff dangling and I could still not locate where the sound originates. There is simply nothing in the dash that could make that sound.
The only thing I can tink of now is that it might be the AHC pump, which is located on the right hand side, just behind the dash. I replaced the AHC fluid a year ago. Could it be that the pump makes this sound when cold? And what can I do to solve it? On the plus side, it is getting warmer outside so I can hardly hear it anymore.
 
Good question, who knows, but I don't think so. The sound seems to originate from the right side of the dash. But it is hard to know exactly sitting on the left side while driving. And although I can manipulate the pitch an volume, it doesn't seem to be inline with the movement of the tach.
 
Still haven't figured it out.. I was thinking. could it be a bad wheel bearing? I don't think a bearing sound like this, but who know's how it pitch changes when the sound travels through the dash into the interior.

Like I said, I pretty much eliminated anything in the dashboard itself so I am shifting my focus to the engine compartment, wheels etc...
 
if it were me. i would pull the fuse to the tach and to the climate control and see if the noise goes away. then add the fuses one at a time until the noise comes back. also the speedometer. is there a small fan that blows cabin air over a sensor to give signal to the climate control????
 
I followed your advice dustbowl and started pulling fuses. I found one related to the dash in the driver side footwell but pulling that one wasn't a good idea. I wasn't able to shift the transmission so driving it wasn't an option. I then pulled two (one after the other) on the passenger side but they had no effect on the sound. So I am guessing this is a dead end, unless I find another fuse that might do the trick. It still baffles me that I am unable to trace the source.
The outside temperature is too high now to reproduce the sound so I guess I will have to wait for a while.
 
Well, it took a while, but it is cold enough so hear the sound again..

So anybody out there the have any idea. I am still at a loss.
 
Thanks paddo, I will look into this. Could you point me in the right direction? Where do I find LCP's method?
 
DeltaT said:
Thanks paddo, I will look into this. Could you point me in the right direction? Where do I find LCP's method?
Click to expand...
Check out a thread by Sonk76 - how to lubricate front axle shaft bushings, both the Slee screw on tool and landcruiserphil's short cut method are discussed.
 
I'd get a mechanic's stethoscope (or very long blade screwdriver) Start under the hood with idler bearings (most likely), working down to the pumps and alternator. It sounds like bearing going bad, if lucky it's from serpentine and not timing belt idlers/tensioners or water pump. Other than bearings; the engine cover and roof rack will make some funny vibration sounds, so don't forget too check them as well.

Slight possibility of pump for brakes or AHC, but is something I've not dealt with.

I take it the nose is present while in park, so that would eliminate the drive train (except transmission).
 
I have this sound only when it is freezing outside and only for a short period during warming up. The sound is not there when the car is not moving (with the engine running, in park or in gear).
I have replaced the waterpump, serpentine and idlers along with the timing belt last winter (about 5k miles ago) but the sound is still there.
I also replaced a cracked exhaust manifold. The engine cover has been off to do this and it seems to be secure.
I can manipulate the pitch with speed and volume with the throttle position (under load) but is is not linear if you know what I mean. It is difficult to explain. It seems that the rpms of the engine has no effect. If I cruise and put the gear in neutral so the engine idles, I can still hear the sound. But as soon as the temperature climbs the sound disappears. It is only for a couple of minutes.
The thing is that the sound only appears when the vehicle is moving. It is almost as if the outside wind from driving is causing a fan to rotate, which in turn produces this sound.
I know what bad wheel bearings sound like, but I checked the wheel bearings anyway. They seem okay and I have the idea that it sounds more like an dirty electric fan of some sorts. That is why I searched under the dash and disassembled and checked the heating system. But I can't find anything wrong there.
I have taken my roof rack (and rear spoiler) off so they are not causing this mystery sound.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom