kitlz

The windshield defrost is set to turn on the A/C as the default. It can be turned off by going through the labarynth of settings.

DunWkg

Like most of the "systems" in a car, the HVAC system has become pretty complex. I'm sure if there were another manual with "sequence of operations" it be helpful to understand the inner workings. To me, the HVAC seems most inconsistent. It seems to change at odd times, like when you headed into the wind it behaves differently when running perpendicular to the wind, yet outdoor air temp is the same. And that is in regular mode, in ECO mode in the hybrid I don't think you can ever know what it is going to do.

I wonder where this sensor is located, before the cabin filter or after? If before, my RX would be in automatic recirculation mode all the time with the amount of pollen in the air this spring. It might make sense to be after the cabin filter to allow the filter to do it's job. Or maybe it's not even in the ductwork. Is the cabin filter considered a HEPA filter?

As far as the air conditioning compressor, there is a switch in the nav display and the manual says it automatically stops operation at 32 degrees and below. So the car will dehumidify with AC until that point even if heating, if needed.

07LexusGuy

From what I understand, if the cabin is very warm upon startup, the HVAC will be in "Recirculation" mode so as to cool down the cabin faster. After the cabin has been adequately cooled, it switches to Fresh air.

You don't have to be in AUTO or have AC on for this to happen, just as long as your desired temperature is much lower than the cabin temperature.

ejm3

This sounds realistic, but makes no sense.
Today was a little cooler (maybe 61 or so) and when I started the car to come home from work it didn't kick into recirculate.
But it makes no sense to kick into recirculate mode if the AC isn't on no matter how hot it is.
All it does is recirculate the really hot air in the car!

happy1977

The fastest way for me to cool inside is opening the windows and blasting the air out for a min or 2 while driving, then I closed the windows and set on recirc mode.

billy44bo

You can run a car AC on somthing other than recirc? On the coast I keep it on recirc all the year long. In the summer and winter we have a lot of Relative humidity in the air in the spring and the fall a lot of pollen in the air . I have to look at the control after about 5 min after you start up to make sure that it is still in recirc. Also we never turn to AC off on the cars here because of the humidity.

ejm3

I basically never want the car in recirculate mode. I want fresh air and it just never gets that hot around here.
In every other car I've owned I don't have a problem shutting it off but in both the Toyota and Lexus its a constant battle!

cruiser

Dont know if this helps but recently i came across a TSB regarding A/C. It had to do with initial ac smell when turned on. I cant find it right now but i think it had to do with the initial ac start up and it would go to fresh then recirculate to avoid the moldy smell. Cant remember if it had to do with outside temp vs inside temp. Has any ody read this TSB?

ejm3

I am fairly convinced that its checking the air temp in the car and if its over a certain temp (not sure what) it automatically recirculates.

This is the only TSB I could find on AC on my 2010 RX:

Nature of Defect:
EQUIPMENT:ELECTRICAL:AIR CONDITIONER
Bulletin Number:
LSB-0128-11 Bulletin Date:
Oct 2011
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Summary:
LEXUS: A CONDITION, EXHIBIT BY SOME VEHICLES, REGARDING THE VISIBILITY OF DUST OR POWDER LOCATED IN THE HVAC VENTS. A CLEANING PROCEDURE HAS BEEN DEVELOPED WITH A NEW DESIGNED EVAPORATOR AND HVAC SYSTEM, TO ADDRESS CONDITION. ( NHTSA ITEM NUMBER - 10042912 )
--------------------------------------------------------------------------------

cruiser

I wish i could find TSB on initial ac smell and the fix

MEP7557

Change your filter to the one with the carbon in it, got rid of it for me.

I have the ability to turn off the recirc, don't all of the RX's?

ejm3

Yes I can turn it off but I don't want to have to change it every time I get in the car.
If I shut it off I want it to stay off unless I turn it back on, just like every other car I've ever driven (that wasn't a Toyota).

Interestingly it was cool and rainy when I left for work and it didn't default to recirculate. But when I got to work it was on recirculate. I'm guessing it hit the magic tempature at some point while I was driving to work and it switched over, despite not being in "Auto" mode..

BobBass

I have an '08 400h and '09 Camry Hybrid and a priority for me was to have this "issue" changed in personalized settings. It's been awhile, but you should be able to have the dealer change the default from this "auto recirc" setting to manual only. Lexus had no problem; the Toyota dealer acted like this was a major hassle - they had to "open up a case" with Toyota to figure it out. Apparently nobody else thinks like WE do.

I want complete control of when the recirc comes on and the compressor, too.

DunWkg

Ejm3 and others,

The next time you are about ready to get out of the car and before you power off, try setting everything (auto off, a/c off, dual on, temperatures (driver/passenger) you want, blower speed, air outlet mode (which outlets you want), and recirculation off, all of this the way you want it. That should be eight things on the climate control with navigation set the way you want them the next time you get into the locked car using your key fob. Now before you get out, memorize your seat setting. At the same time, the car will memorize the climate control settings for that fob.

If your second fob is memorized differently, then when you open the locked driver's door with that fob, the car will revert to the climate control settings memorized for that fob.

I'm not sure of this next comment, but it's what I'm guessing happens: if the car is unlocked from the passenger's side and the passenger's door is opened first, the car will revert to the last settings before the car was turned off.

Marqevans

I've got to say I miss the manual climate control buttons I had on my RX's without NAV. The time spent with your eyes off the road while trying to change settings through the screen is much greater than quickly pressing a button on the dashboard.

Actually upon further review only the AC and dual temp options are missing.