Brand new yukon xl 2018 5250 mills, the ac takes a long time to cool down at least 15 to 20 minutes. i am in miami,fl and with 95 fahrenhait and 3 kids in the car. gmc after 6 weeks of trying to fix the problem just let me know that the ac is working as design and there is nothing to do. in this 6 weeks i got a yukon as a loaner and the ac was working perfect, the ac took 3 min to cool down every time you turn it on.