To help home wine makers deal with the problem of keeping fermenters cool, consider trying a cooling coil.
A cooling coil is essentially a stainless-steel coil; you can place it in your fermenter and run cold water through it to cool the juice or must.
Fantastic homemade wine resource: WineMaker Magazine published this great tip in 2002:
The first step is to make a coil out of one-inch or 1.5-inch stainless steel tubing. Coil the tubing into loose loops within your fermenter. CAUTION: do NOT use copper, as the Ph is likely to cause the copper to leach into the wine.
Next, weld on standard garden hose fittings. Once you can hook the loop up to your water source, turn the water on slowly and you have a constant source of cool water travelling through the tube and cooling your juice or must. It works much like the tank-cooling jackets large commercial wineries use but on the inside!