New Member, The Devil's Screech (2 Viewers)

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Joined
Aug 11, 2025
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1
Messages
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Location
Austin, Texas
Hey everybody!

Last month I picked up a southern owned, 2005 LX with 243k on the dash in Galactic Grey. My dream car. I've wanted a 100 series since high school, and always loved the funky LX headlights plus the subtle blue specs in the (considering the years she's roamed the earth, pretty beautiful) paint. I am the fourth owner, although the previous 3 took immaculate care of her. Metal heater T's, timing belts replaced on schedule, regular fluid changes, etc. Her only fault is that during regular service for the 2nd owner, the dealership accidentally replaced the AHC hydraulic fluid with brake fluid, killing the whole system. So now she rides on LC100 shocks.

I've spent the past month baselining. Differential and transmission fluid changed, along with the oil. Timing belt and heater T's were already good to go. The only "true" mechanical issue (the other issues being worn door lock actuators and mirror controls, which I can live with) is a leak from the rear main seal, but I'm going to put that off for now!

In summary– She has no rust. She has no faults (that I'm not willing to accept). She is perfect, except that the devil lives inside of her.

Whenever the A/C is on, more specifically whenever the fan/blower is running, there is a satanic screech that comes from the passenger side of the dashboard. However on further inspection (removing the glovebox, searching with a stethoscope), the sound actually comes from closer to the center of the dashboard, almost behind the nav. It sounds like a busted DVD player struggling to read a scratched disk, crossed with a dentist's drill. The noise, and whether it is DVD player or drill or both or none, is never constant and was actually gone for a week or two. It has since returned. The dealership (a last resort, but should tell you how tortuous this noise is) diagnosed it as the non-OEM blower motor having fits. A new OEM motor and a thousand dollars to the stealership later, the noise has not changed at all.

The previous owner had a BT45-TOY installed by Troll Holes in SC (a reputable shop by all accounts). When I asked him about the noise during the test drive, he told me it was only the Bluetooth searching out my phone to connect and once my phone connected it would go away. So that's not true (I shoulda checked, lesson learned), but it can be stopped/started on a dime by whether the A/C blower is on (and living in Austin, I want it on). My guess is somehow the BT45 has been possessed by the devil and/or is wired into power from the A/C blower. Or it's something else entirely.

Video attached below. From 0:22 - 0:52 it's just the dentist's drill from hell.

Screech Video

Besides that, I love my LX. No finer vehicle did God put on this earth!
 
Do you use the Auto function for HVAC system? Have you tried switching the AC to heat? Do you get hot air when switching to heat?

All that to say maybe it could be the servo motor that controls the hot/cold air mix which is in that location.

I highly doubt its the BT45 causing this
 
I'm running the BT45-TOY as well in my 2002 LX 470. It connects into the head unit using the stock connectors. Just snapped a couple connectors open and snapped them in the new wiring provided. The wiring provided with the BT unit wasn't poor quality to my eyes.
I really doubt it has anything to do with the BT unit. Just to rule it out though, take it out and see if it fixes the issue. It takes 10 minutes to get behind the head unit and disconnect it.
My guess is you need a good cleaning in and around the filters and the blower motor. Do it yourself to be sure. I used to park my LX under a bunch of pine trees for a year and every now and again a pine needle would make it to the blower motor. You would be surprised how loud one pine needle can get. Before doing this though, test if the sound changes frequency with the speed of the blower. That should be a good indicator that it's related to the vents / blower or not.
Hope this helps.
 
can you post a video of the sound?

have you tried popping off the trim that includes the center vents to make sure there isn't something physically obstructing the air flow and maybe making it whistle?
 
Do you use the Auto function for HVAC system? Have you tried switching the AC to heat? Do you get hot air when switching to heat?

All that to say maybe it could be the servo motor that controls the hot/cold air mix which is in that location.

I highly doubt its the BT45 causing this

I do use the Auto function a lot. The noise is still there when the heat is on and the heat does work, although when running at a consistent temperature (no Auto function) I think there may be less noise? It's very hard to tell. The servo motor is something I had not considered. Going to dig into the FSM. I also (and based on everyone else's comments) am starting to think the BT45 isn't the cause. Previous owner may have been leading me down a false rabbit hole.

Thank you.
 
when you swtich the radio off does it stop ?
No, the noise is not tied to the radio (or tape, CD, etc.). It is only tied to whether the fan is running.

I'm running the BT45-TOY as well in my 2002 LX 470. It connects into the head unit using the stock connectors. Just snapped a couple connectors open and snapped them in the new wiring provided. The wiring provided with the BT unit wasn't poor quality to my eyes.
I really doubt it has anything to do with the BT unit. Just to rule it out though, take it out and see if it fixes the issue. It takes 10 minutes to get behind the head unit and disconnect it.
My guess is you need a good cleaning in and around the filters and the blower motor. Do it yourself to be sure. I used to park my LX under a bunch of pine trees for a year and every now and again a pine needle would make it to the blower motor. You would be surprised how loud one pine needle can get. Before doing this though, test if the sound changes frequency with the speed of the blower. That should be a good indicator that it's related to the vents / blower or not.
Hope this helps.

The BT45 might have been falsely blamed here. I'm going to go back there and clean around the filters/blower motor. The thing is that the noise doesn't sound mechanical or like anything is stuck, it sounds like a computer. But still good to get back there and clean anyways! Thanks for the help!

can you post a video of the sound?

have you tried popping off the trim that includes the center vents to make sure there isn't something physically obstructing the air flow and maybe making it whistle?

There's a link to a video of the sound at the end of the original post (couldn't figure out how to post a video directly to mud).
Going to pop off the trim to disconnect the BT45, will look for obstructions. But again, it's not a mechanical, obstructed sound. It sounds like a CD player or computer. Thinking it might be a bad servo.
 

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