You can find this fare available daily starting next week through the middle of August. This deal is around a $70 price drop from the usual price and books into American's Main Cabin, which allows a regular size carry-on.
Searching on AA.com, I found seats departing CLE on Saturday, August 4 and returning from CZM on Tuesday, August 14, 2018. Other travel dates are relatively easy to find, as this is a pretty flexible fare.
If you'd like to head somewhere else other than Mexico, we have a full list of available deals departing Cleveland (CLE) here.
Need a room in Cozumel? Have a look at what's available for the sample dates above on Hotelwatchdog.