I usually don't have issues, but when I do need to cool things down, I have a couple of the 1L jobo chemistry bottles, filled with water that I keep in the freezer - if I put those in a couple of the chemistry cells, I find that it can keep the bath at 20C for long enough to develop several batches of film. I keep the ice-bottles as far away from my developer as possible so that there is not a local cooling effect.