Damp rid helps but I still get condensation (Florida). I try to limit opening as best I can, make sure you seal well around the collar and any holes to limit the moisture getting in. I also keep bar towels handy and wipe down the sides when I'm servicing the keezer and fermentation fridges (especially when I have an active fermentation going) as it really helps cut down on the condensation that ends up on the floor of the freezer. For that I just toss a bar towel down there to absorb the moisture. To some extent it is something to live with, keep it clean and wipe down regularly and you should be fine. I have not had any mold issues despite the warm humid climate.