Just to confirm what you are looking for. You mean the switch/button to turn the A/C on and off? If so, take a look at the picture below. You will see the snowflake on the left knob. You need to push that knob in and it will turn the A/C on.
Yours may not look identical to this as I believe this is a 2013 but it should be similar.
Feb 1, 2021 at 6:20 PM