I live in Phoenix, AZ with a 2017 Aria 3901. In 100+ degree temps, the ACs do cool off the unit so long as you use the night covers on the windows and run them both full blast. It takes them awhile to 'catch up' and the temp inside the coach rises very quickly if you let them shut off. When driving in high desert temps, I do find that it is hard to stay cool in the drivers seat...even with the chassis AC running in addition. When over 100+ degrees, I prefer to drive at night.