I just got a large standing freezer (for food).. I was thinking of mounting lights on the sides and a couple on the top, then setting it on a night timer. I just have to see what kind of warm temps the freezer is capable of. I don't want to turn anything into ice cycles.. I figure just having it run for about a half hour at night will cool the chamber enough to have a level cold temp for the duration of the night.
that would be a good idea for cooling, the problem though would be when you had the lights on and the accumulating heat from them, as well as the need for good circulation. Unless you like to keep moving the plants in and out of the freezer, you will have to modify it to fit the needs. Like adding circulation fan, air vents, put the lights on the outside and cut an opening and cover with glass. It may be simpler to just make your own grow box and add the cooling compressor from the freezer. I have made another highland grow box the same way, but using peltier cooling. They make great display pieces. Could make one cheap since you already have the cooler