Air Conditioning Pulse Or Pulsing Sound

[snowabode]

New 2008 IS 250 AWD.

When the air conditioning is on and the vent is open (not set on recirculate), there is a pulsing sound. It's almost as if I can sense the air pressure changing. It sounds like you're five or more cars from a train while it's crossing; not too faint but present.

To stop the pulsing sound: open a window, set to recirculate or turn off the air conditioning. It’s definitely not the ticking sound from under the hood.

Any opinions?

[bartkat]

I think you'll notice that it only happens when the blower is on it's lowest speed. I believe it's just barely overcoming the resistance of the filter and plenum and setting up a pressure wave. I think it's "normal" on all the 2nd gen IS.

[smooth1]

Yeah, I've noticed it also, and I also noticed it happens if you slide open the moonroof. It's definately cabin pressure from them. Have you tried opening the pass thru from the trunk to the cabin? I noticed it's alot less, you just have to leave the armrest down in the back seat. No big deal.

[IceZ]

I've noticed this on my 08 AWD as well, but it was when i opened my rear windows.

[Gaugster]

Yeh,

Both sounds whether from the A/C fan at low speed or an open window or moon roof are generally called ‘buffeting’. The buffeting from the A/C is unfortunate as that can usually be designed out. Luckily it is not very loud. My car does it with the A/C set to vent or recirulate. The other, more common, buffeting is just fixed by opening more then one aperture i.e. window, moon roof etc...

Regards,

[Sidney07]

So I'm NOT crazy! Thanks for the tips! I've been noticing this since we got the car. I thought it was just me...my wife says she doesn't notice it...silly girls!

[thalter]

I am sooo glad I'm not the only person who noticed this!

I can't always hear it over the stereo, but when it happens, I can feel buffeting in my inner ear (if that makes any sense). I've thought about trying to crack a window to equalize the pressure, but lowering the rear armrest sounds like an interesting idea.

[snowabode]

I'm taking this issue to the dealer and will see what happens. I hope that others will, too. I'll keep this forum informed. It shouldn't do this.

[Sidney07]

Good luck with that...they will just refer you to a local mental health professional :)

[bartkat]

Never really thought of it as an issue.

[snowabode]

Bartkat's response(s) that he didn't think of it as an issue and that it's considered normal for the 2008 IS 250 seems to be the opinion at the dealership, too. One tech said he could hear it and another said he couldn't. They found nothing wrong with the air conditioning system, the ventilation or the fan. They told me they made no adjustments and that I should keep an eye on things and keep them informed.

[Meesha]

So I'm NOT crazy! Thanks for the tips! I've been noticing this since we got the car. I thought it was just me...my wife says she doesn't notice it...silly girls!

I've noticed that sound from Day 1!!

It was winter so I didn't have A/C on. But this sound comes from the fan, I think. If I turn off the fan, it stops. But normally I set the fan to a low setting and I can hear it.

I complained to the dealer but they don't hear it.

My friend didn't notice it.

It's not so loud but if you are the owner of the car, you hear it ;) I came to a conclusion this is the way it is... oh well.

[snowabode]

I tried to take the general feedback to heart and ignore the sound but I can hear it almost all the time, especially when idling. The dealership acknowledged that the effect exists and said there was nothing more that can be done. They claimed to have contacted a regional techinician who said that it was known but a fix did not exist. I asked the dealership if there was anything else I could do and they told me to call Lexus customer service, which I did. Lexus called me back two weeks later and said that they had contacted both the dealership and their tech team and that my issue has been reported and will remain on file without a current solution.

Perhaps I should mention that in spite of this problem, this is the most wonderful car I have ever owned.