I have a 2005 RX400h for a couple of years now. The car run fine and I am currently on my first holiday with car.
What I noticed that, with warm weather or/and when my trailer is behind the car, the air intake button sometimes automatically switches to re-circulation. At that point I can't switch back to normal mode. Only when I turn of the AC in the climate menu, the air intake goes back to standard (light off).

In the manual it states:


So this looks a bit scary. Both my inverter and engine liquid coolant are at normal levels. Also the temp meter inside the car gives a normal range.
For me it doesn't feel good that no fresh air is blown into the car for a while.
Should I be worried or is this normal behaviour?

 

Where do you live? What is the outside temp when it happens?
PS: You already posted the answer to your question from manual.

 

Netherlands Europe. On holiday on France where temperature is around 30 degrees. But no overheating symptoms are there, maybe it is a faulty sensor.

 

No, it's not a faulty sensor. This mode prevents a car from overheating. RX400h has 2 coolant systems - for ICE and for Hybrid convertor (you can see ICE temp next to speedometer).
A/C is electric and powered by hybrid battery, so, when car is loaded and the outside temp is high then there is a risk that the hybrid system can be overheated and fail.
PS: I had the same at extreme conditions only: 35+C outside and "insufficient airflow" to cool the engine (long ICE idling at parking lot with AUTO A/C ON or driving uphill on a mountain road).
PPS: What are the driving conditions (speed, traffic, uphill or not, only while towing, etc.) when you have this problem?

 

I noticed the first time in this holiday when towing the caravan 1600kg. During holiday I also noticed it when I drove trough the mountains at 32 degrees celcius.
Tomorrow I will drive home without the trailer (800km). So let's see what happens. Tomorrow should be cooler in temp, around 24 degrees celcius.

I don't know what I can change, because I can of course only see the ICE temp and not the inverter.
So I don't know if something is faulty. Can I check if coolant goes trough the convertor?

 

Do you have towing package?
https://www.clublexus.com/forums/rx-...threads-4.html

Just turn OFF A/C while driving in mountains uphill with caravan. And open the window to have fresh air

IMHO don't worry. It (invertor) would fail very fast without coolant.

PS: How often do you change transmission oil? You should do it regularly if towing a lot.
PPS: As I remember, transmission and inverter have a common coolant lane/system.

 

​​​Don't know. It is a 4wd with 2 electric motors and can tow max 2000kg. I have no clue if I have the towing package. I will check.

Never did it since I bought it almost 3 years ago. I also am not a fan of doing this. I let it do 1 time before on a XC90 v8 and also let it flush. It completly ruined my transmission.
But I will look into this.

Yesterday I cleaned the air intake filter under the dashboard glovebox. It was completly covered with oak leaves. Really a lot. So I cleaned it.
Next thing I did is clean the 3 air intake filters under the back seats for the hybrid battery air intake. These were also dusty.

Today I drove back from my holiday adress without the trailer (700 km). It was between 26 and 32 degrees celcius outside. The whole car was fully packed, but I made sure air could reach the air intake filters under the back seat. Only once during the drive the recirculation went on. I directly looked what was wrong and my wifes hanbag fell in front of the rear blowers, so it was limiting the cold air coming knto the air intake unde the rear seats.
After removing the bag, the recirculation switched of after 5-10 minutes and didn't occur anymore.

I think that the temp and the air circulation inside the car is very important. So 2 things I am going to check:
- Is the AC coolant still ok and blowing enough cold air
- Are all the air vents still ok and isn't it blocked somewhere

 

Don't worry. RX400h has eCVT. It will not fail after oil change.
https://www.clublexus.com/forums/hyb...ial-plugs.html

Be careful. Hybrid battery doesn't like "overheating" - could die very fast.

 

Already great posts.
Can I plz add, there is a good thread on here about replacing the Hybrid Battery cooling fans.
Some people may do it for preventitive maintence if they wish, depending on mileage and age, it's just a matter of time in the long run.

 

PS: The tool below has an option to select the Temp when Hybrid battery fans will turn ON (ie you can start cooling earlier). The main purpose of the tool is to find if the battery is still alive.
https://www.clublexus.com/forums/rx-...l#post11120000