Following my earlier post, I now have an answer to the problem. Lexus have had my vehicle for a couple of days and have found that the spinning noise is caused by a malfunctioning cooling fan housed in the audio unit. The audio unit will be replaced under warranty.

 

Interesting! What year is your RX?

 

It's a 2013.

 

My b2b warranty is up so I guess I'll have to live with it. Seems to be a problem with the 2013s

 

The wife started hearing the noise several weeks ago from her 2013 with 50K on it. We live just outside Philly and it is starting to get colder now. I just took some time today to really listen for the sound. It is definitely coming from something that is rotating. It is coming from just behind the nav/audio components. Though we had one CD in the unit (that we never use), I removed it with no change. This whirring sound can be heard with the ignition set to on and without the engine running and also continues for several seconds after the ignition is shut off. I made sure that there was nothing else running (heater, seats, radio etc.). I would agree that this sound is likely coming from a cooling fan, but for what is the question. Seems similar to the same sound you would hear when a computer cooling fan starts to go bad. I do not see this as being a self healing problem. Since there seems to be quite a number of us with this very same issue, could someone please let us know if/when you had it repaired (or maybe even addressed it yourself) and what specifically was involved. any help would be greatly appreciated. thanks.

 

The good news is that you can reproduce the issue. It's much harder to fix when it's intermittent.
My initial suspect is the Nav system's cooling. I would look for the Nav/Stereo fuse and pull it. If the Nav stops working and the noise goes away, we got a solid lead. Of course, it also breaks the climate control (thanks Lexus!), so it does not completely eliminate it from the equation.

 

 

I've had this issue now for about 3 years, only on extremely cold mornings when the car has been sitting over night. At this point, I don't really seem bothered as it doesn't seem to be doing any harm. Start car up, whir sound, and then slowly stops after about 3-4 minutes.

I just realized I was the one who started this thread back in Jan of '16! One of the posts mentions it being the hard drive warming up.

 

Cold weather is back and so is the very same noise. I believe now that it is the cooling fan in the back of the nav/stereo unit. I thought about pulling the fuse for the nav/stereo but then I would loose all presets (maintenance, radio, phone, addresses, etc.). I did not hear this sound all summer so if it is the cooling fan and it only gets grumpy in the winter yet still works fine in both winter/summer, i can live with that. I even considered pulling the entire unit (not very hard really) but to actually get to the fan seems to require dismantling the entire unit. that is currently not an option for me. I called Lexus about this issue and the person I was speaking with said he had no report of this being a problem.

 

I disconnected the battery a few times. You don't loose anything, other than the rear door has to be opened and closed once manually.
In fact, you have to explicitly delete all of your personal information. I just had to go through all of that to clean it up.

 

The 2013 RX350 is back at the dealer again to have this issue revisited. Having paid $700 to have it fixed, I am sticking with it until it is resolved. Since the noise continues after the car has been powered off, Lexus thinks it could be the "recirculation servo" so the plan is to replace that and see if it helps. If I have any luck, Ill let you know.