Is neck sweating in a cooler counterproductive?

I have a couple of heifers that are getting a little fat necked and have contemplated starting to sweat them. However, they are in a 65 degree cooler and currently growing great hair with 30 more days to the show. So, is it counterproductive to sweat in a cooler? I would do it at night but it's hotter than the cooler and I like to let them relax and eat hay. thanks