I would like to know what is the best practice.
I leave mine set to "AUTO" , I do not set/press "AC". I just turn temp **** to desired temperature and it kicks on AC or Heat as needed.
On my previous vehicles I would press "AC" to On when needed - but then shut off the "AC" before shutting off the engine.
I always thought I was saving additional load on the engine while starting with the AC compressor off and maybe saving excessive compressor wear also.
Will I cause more wear & tear by just using "AUTO" ?

 

ChatGPT said:

✅ "AUTO" Mode in the 2025 NX 350: Best Practice

The climate control system in your Lexus is fully automatic and intelligently manages the AC compressor, fan speed, airflow direction, and heating to maintain your desired cabin temperature with maximum efficiency. When you:

• Leave it in "AUTO"
  
• Set your preferred temperature
  
• Don't manually press the "AC" button
  

…the system automatically engages or disengages the AC compressor as needed—even if you never touch the "AC" button.

🔧 Why You Don’t Need to Manually Turn Off the AC Anymore

In older vehicles:

• The AC compressor was belt-driven and engaged by the engine.
  
• Turning it off before shutting the car off reduced engine startup load.
  
• It may have helped avoid wear on older mechanical compressors.
  

But in your 2025 NX 350:

• The AC compressor is an electronically controlled, variable-speed unit.
  
• It only runs when needed and ramps up/down gradually.
  
• There's no mechanical clutch "shock" like older systems had.
  
• The engine control unit (ECU) ensures no excessive load at startup, regardless of AC state.
  

❄️ What Happens When You Use "AUTO"

• If the outside air is warm and you set the temp to 70°F, the system will activate the AC compressor, even if the "AC" button light is off.
  
• If you set it to 80°F on a cold day, it will engage the heater only.
  
• In both cases, Lexus’s logic protects the system components from unnecessary use.
  

🧰 Final Answer: Will AUTO cause more wear and tear?

No.
Using "AUTO" does not cause more wear and tear. In fact, manually overriding the system unnecessarily could reduce efficiency and comfort.

 

Wow ! Thanks
Very clear answer with detailed explanation

 

Auto ECO . If you floor accelerator then same power as other modes. This is how I run, but it is a personal preference. Best IMHO for economy on air conditioning.

YMMV,
MidCow3

 

Perhaps I am not setting the Auto function correctly, but when it is on the fan speed is too high for my liking. If I adjust the fan speed lower then the Auto function stops operating.

 

Yes the fan will turn way up to get you to your destination temp set. So if you get in your car in July when it's really cooking outside and your interior is even hotter the fan will go to max to get you to your temp setting then slow down to maintain. Do keep in mind that the temperature probe is on the dash somewhere, it looks like a little grate or vent, I think its to the left of centre maybe straight below the push button start. Anyways, when the dash material itself is hot it will influence the reading captured for the interior temp and take a little longer to cool down the interior material ie the dash itself. But eventually it does slow down the fan speed. This is the bit that I get bothered by and become too anxious myself so I take over and max out fan, get comfortable and slow fan down myself. In other words I become 'Auto' .

And don't forget it works the opposite in winter. If you use the dash vents and not the floor it'll keep blowing hot air out the vents way too long for my liking as it waits to heat up the dash. I mix blend floor and dash or defrost and floor to get the dash warmed up quickest.

As an option you could direct air to nott blow right upon you but maybe up towards roof.

 

AUTO is AUTO In your case set the air vents, fan speed, recirc, and temperature to you liking, but you can't program AUTO ...sorry

YMMV,
MidCow3

 

I do 🤓 (not a proposal)

 

Fan speed is usually a consequence of the temperature differential between the HVAC setting and ambient. If you want to adjust fan speed without disabling auto, simply adjust your HVAC setting a bit closer to ambient and the fan speed with reduce.