360LexusEs

Hi everyone, so for the past 2 years my 2010 RX 450 H has been making a purring sound coming from the passenger side vent. Initially it was only noticeable on windy days but slowly it has started when I drive the car occasionally. I've brought it to the dealer twice for this complaint on one occasion they couldn't duplicate it, on the second trip I took it on a windy day and they were able to duplicate it with the car parked and engine shut off but said they didn't know what it was and if they couldn't find anything I'd be charged.

Here are some video of the sound and where its coming from does anyone have any insight into what this could be? Thank you!

Droid13

Does changing the fan speed, or vent mode settings make a difference?

My first guess would be some debris rubbing on the fan, but fan speed should be a clue.

360LexusEs

Happens with the fan completely off, also happens with the car just parked and the engine off. The only time its noticeable is on a windy day or when the car starts moving from a stop occasionally

Droid13

Ah...

My second guess then is some vibration caused by pressure differences from the wind blowing over the vent intakes. If it's been happening for years, it's likely not to be ordinary debris. Perhaps a loose panel within the ducts. This is where I would try to see if the noise occurs with the vents in different modes, like floor, defrost, etc. and confirming that the airflow is actually respecting the chosen mode for all vents. This might give a hint if the duct control is somewhere inside not adjusted or setup properly.

Clutchless

I think you may have leaves or other debris in the ventilation fan. I would remove the cabin air filter, inspect the area and try to vacuum it all out. You may have to take more apart to get at or closer to the fan motor to see if anything is in there.
I had this on a 1994 Mazda and found lots of leaf debris on the ventilation fan blades. Once removed it was quiet again.
You can change the cabin filter yourself, it takes 5 minutes.

paperthin

Interesting. I have had this purring also but it only happens on really windy days. The sound in the video is a bit more faint than what I experienced, but then again mine only occurs on really windy days. I traced it to the fabric in the wheel well on the passenger side. Even though it doesn't look like air can pass through or around the fabric, perhaps only through the vent in the wheel well, when I put my hand on the fabric at various places and pressures I can alter the sound that is resonated up. This drove me bonkers for a bit. This might not be your problem but maybe worth a check.

tempestv8

I sat in my car for a while but couldn't hear anything like what was recorded in the videos above. I did hear the blender valves moving around, but they were quite distinctive noises.