This fare is available starting just after Thanksgiving in late November with departures valid any day of the week (if available). You'll have the best luck finding seats for mid-week travel though. You must be flexible with dates in the springtime to locate this fare, but if you search on the AA website, you should be able to find a $75 one-way fare that you can build around.
As an example, I found seats departing ORD on Sunday, January 20 and returning from PHX on Friday, January 25, 2019.
Need a room in Phoenix? Here's what's available for the listed dates on Hotelwatchdog.