Hi everyone. I just picked up a 2024 RX Premium+ last night. I've noticed when I start the car the A/C "button" on the screen is not selected automatically, leading me to believe it's blowing the air but A/C isn't actually on. I'm used to my cars always turning this on automatically upon starting the vehicle. What am I missing?

 

My experience is that, when the HVAC system is on, the A/C is turned on automatically as needed to cool the cabin, but not when heat is needed. The A/C can be switched on for dehumidification when it's cold outside, to prevent fogging of the windows. A/C is also turned on, and the engine is started, when the front defogger is turned on. This is all scattered through the manual.

I tend to use the register settings and A/C to defog so that the engine does not start. I imagine that, in colder temperatures, the engine is needed to quickly defog.

 

I had to do all kinds of test to finally understand how it works. The lights on the AC touch buttons are not intuitive but this is how it operates:
1- If the AC is off when you turn off the car, next time you turn on the car the AC remains off.
2- If the AC is on when you turn off the car, next time you turn on the car the AC comes on but the AC touch button is NOT lit.
3- If the AC was off and you start the car and turn on the fan, it starts the AC, if you touch the AC touch button, it turns off the AC but the fan stays on, until you touch the AC again to turn it on.
4- If you just use the Auto, then it always strays on, whenever you turn off the car and start the next time.
5- Note- If you have the 350h or 450h, and you have the AC ECO mode on, the AC is running but at the ECO management power, meaning it regulates as how much the AC compressor is working.

 

Lexus SSA, If it's cold out and you turn on the fan or use the auto setting are you saying the car still turns on the A/C ? Also on the hybrids in Eco mode, doesn't it cycle off the compressor when it achieves the set cool temp? It would seem that the car should know when its cold outside and bypass the compressor.

 

Go to your settings and vehicle customization. under HVAC you can customize if you want AC to be controlled automatically.

 

1- If you turn on the AC in cold weather, it still turns on the AC compressor in order to use the dryer part of it to dehumidify the cabin and get rid of the internal fog on the windows.
2- Yes, the auto / ECO mode regulates as when to turn on the compressor and turn it off.
Just a note, that these are my personal understanding and tests I have done. Not claiming to be the expert on Lexus AC management.

 

We should probably differentiate between A/C cooling when it's warm outside and A/C dehumidification when its cold outside. My experience is that A/C dehumidification is not automatic in Auto Mode, but A/C cooling is automatic in Auto Mode.

 

i have my AC set to off, but AC in automatic in customization. When I turn the fan off and the windows start to fog up I just turn Auto on and with AC light turned off the windows de-fog.

 

This drives me absolutely nuts, even though even if the AC light not on it still seems cold, but I think OCD of me. On my prior RX never used auto, but the AC light would stay on only if I shut it off.
I feel like it part of some emission savings BS they are putting in these cars!

 

Just a quick note that the AC button has 3 modes:
1- Completely off (nothing is on )
2- AC lettering is on only (Auto on)
3- AC lettering in on and a blue light is on (The AC is on manually)

 

The issue is I don't use auto, so I would like the AC lettering to stay blue and not have to press it every time I start car.
However even with the no light it does seem cold, so I don't know. I even checked if it could be programed and it can't

 

That is the problem we are talking about. You start the car, the AC is on but the blue light is off.
Try turning off the AC ECO mode in the AC set up screen and see if then, the blue light stays on when you start the car the next time.

 

The un-intuitive indicators (post #10) drive me nuts, too.

I try to limit A/C engagement as it reduces POWER... Over the summer I thought we had turned it off for the trip, yet a puddle of A/C condensate dripped from the area of the RF door sill in spite of our settings.

 

This. In Auto mode, everything shows a median value or doesn't show what it's actually doing. For instance, the fan speed will be in the middle no matter what the fan speed is. It also doesn't show which vent the air is coming out of. So even though the blue light isn't on, the AC is on.

 

All my previous non-Lexus vehicles have always turned the AC automatically on on vehicle startup if that was the last-used setting, but my RX350h does not do this. Is this just not a feature that Lexus vehicles have, or am I missing something?