I did this for my pantry, which also houses my home entertainment devices. Temps would like to 100's; with this fix, they only get to mid-80's.
Hot air rises to the ceiling; you need to get that hot air out. I did this by using two small computer fans to pull air out of the pantry. I cut a hole in the drywall, then made a simple wooden box to fit in the ...
I put two home made DIY olla clay pots with water in my pantry and it cooled the air in the room considerably. I was very surprised.
If your olla pot is sealed good, it is sufficient to put the pot in a bowl to catch up the bit of water that seeps through the unbaked clay very slowly each day.