Update: Problem fixed!
Thanks to responses, I asked the dealer to recharge the AC and the noise went away. The tech did not think recharging would fix the problem so I had to promise not to hold the dealer accountable if the noise remained.
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Hi,
Could someone tell me what would cause this screechy noise.
The noise comes from behind the brake pedal when the AC is on.
Turn on your speakers and watch the video. Thanks.
http://www.youtube.com/watch?v=reOvuMdkx34

 

I think i get the same noise......I always thought that was normal.....hmm

 

The first thing you need to know is if it is associated with AC only or is it a fan or duct position/air flow problem. Does it also do this with the AC off but when you turn the fan on and off? The duct system pressurizes when the AC goes on and maybe its a simple air leaks that whistles slightly in that area. See if turning the fan on and off with AC off makes the same sound? Also try changing the duct system flow points to defrost only or to floor only air flow and turn AC on and off and see if it changes location or sound. Does the sound change when you change between inside air return or outside air feed? Check the outside air intakes for any obstructions. Check the cabin filter and fan that's under the filter to make sure its running smooth and not partially obstructed or rubbing on something. Vacuum that area out.

If all else fails put some ZZ Top into the cd player and crank it - Tres Hombres will do the trick : )

 

During the video, only the AC is turned on/off. The fan remains running.

 

I've confirmed that the fan stays on when the AC button is turned off.
The AC button just turns off the compressor. So the noise is not related to the fan or air flow.

Also, on another forum, I found a similar thread.
http://us.lexusownersclub.com/forums...howtopic=57647

From that thread:
Refrigerant is compressed into a liquid by the compressor.
It goes through a metering valve inside the car (picture an atomizing spray bottle in your mind) and this then feeds the evaporator.
Its the conversion from liquid to gas that creates the cooling (or absorption of heat)
that goes on in the car (behind the dash in the blower box).
You might just be hearing the gas atomizing at the metering valve of the evaporator coil.
Maybe you should turn up the radio.
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If the noise is normal, this car may not be for me.

 

If you can get to the part that is making the noise there may be some things you can do with insulation or foam to deaden/reduce the sound somewhat. I almost never have the stereo on in my car - and in Texas my AC is almost continuously but my car is silent as a tomb. Can't hear the engine in fact its difficult to tell if its running at idle without looking at instruments.

 

Well winter is coming up shortly anyhow so i doubt you will be getting much use of the a/c for much longer.

You can always do what i did. Sell it and upgrade to the LS460 .

 

Does the dealer hear the noise and not know what it is?

 

The first time I brought it to the dealer I just described the problem to the service agent. He said in the XX years he has been there, he never had this complaint before.
So I dropped it thinking maybe it was me.

A few months later I returned to the dealer. This time the agent called a service tech to go out to the car with me. The tech and I sat in the car for a few minutes, listening. The meeting was non-conclusive, meaning either he couldn't hear it or thought it was not easily diagnosed.

The reason I created the video was to determine if the noise is normal for the LS430 or if there is a fix for it. I find it hard to believe this is normal for a car that prides itself on having a quite interior.

 

I have the SAME EXACT NOISE! Let me know if you figure it out! I brought it to my dealers attention and he said it was normal....

 

Yeah its weird. My LS 430 never did that. Wonder what the cause can be.

 

Do you have driver & passenger seat cooling and is it on or off? Any changes when engine is on or off? Same noise when you change the air flow (direction/volumn)?

 

Yep, I hear it too. It's the sound made by the A/C as described earlier. I've had other cars where it was louder, like my 02 Dakota. Wow, what a vote of confidence.

 

I have the same issue as well and was just blindly guess it had to do with the refrigerant cooling. I just bought the car a few weeks ago and need to change the cabin filter, so perhaps that could also be an issue. Maybe I'll play with mine after work as well and see if there is any resolution to be had. I agree with the above comments that this should not be this audible within the car.

 

This is normal. For some cars its more noticeable than others. Just a sound made by the A/C activation thats all to those who notice it. Those who don't may have less noise from this function or just haven't paid it any attention just thinking as I do that it is a noise that happens when turning on the A/C, nothing more.

The time for concern should be when you hear another sound other than the one in this video or the A/C stops working! HAHAHAHAHAHA! Just normal sounds and because we expect Lexus' to be so quiet we over analyze any noises at times. At least sometimes I do!!!! HAHAHAHAHA!L.G.N.M