A/C Switch - - - why ?

Don't all cars with A/C have an A/C switch? If the ambient outdoor temp is "cool" you can turn on the fan without A/C to get cool air in the cabin with minimal affect to your mileage. If its hot outside and you want cool air in the cabin, A/C needs to be turned on and you will take a hit on mileage

 

It's a feature, not a bug. And I'm not using that in a sarcastic way.

The standard mode prior to the gen5 was that the car controlled the bulk of the climate settings, but it left overall control of the A/C compressor to the driver. Honestly, that's not really needed or wanted anymore by the vast majority of drivers, so Toyota has changed things in the current generation of cars.

Now, the car controls the A/C compressor like everything else by default. This is what you're experiencing. But Toyota also understands that some people still want to control the A/C like before, so there's a setting to do that. If you go into the climate settings on the infotainment unit, you'll find a setting called 'A/C mode with AUTO'. It's set to ON by default. If you want your climate control to behave the old way, set it to OFF. Basically, the setting indicates whether AUTO has control of the A/C or not. If you do this, the A/C button will work just like cars you've had in the past. When the A/C light is on, the compressor is enabled(if needed). When the light is off, the A/C system is disabled.

Now if you usually want AUTO to have full control, but you encounter a situation where you want to shut off the A/C quickly without going into a bunch of menus, you can do that by pressing the A/C button twice. The first time overrides AUTO and turns it on, the second time shuts it off. It will stay shut off until you press AUTO again, which let's it take back control.