I know that I started a thread about cooler temps, and how to control them about a month ago.
The whole thread is out there in cyberspace just waiting to called, it's cold and all alone, it just wants to be loved too.
It is even in the Humidor section, if that helps....
but, the advice I was given was this. Ice packs wrapped in a towel on the out side of the cooler. So this is what I did; I took 8 20oz Gatorade bottles filled them water and froze them. I run a 4 bottle rotation, 4 on the cooler, 4 in the freezer and I switch every after noon. This keeps the temp any where from 65 in the morning/night to 75 at the heat of the day. It is a bit of work to keep up with it all but it works, and that is all that matters to me.
The other thing I USED to do is take a wash cloth, dampen it with water, and then freeze it inside a plastic ziplock baggie.....and then take this baggie and put it underneath my humidor. It helped lower the temperature by 5 degrees......but it was only a 50 count desktop humidor.
This sounds like a good idea for home use....
Tim