Although the idea of a built-in climate control taking the place of heavy winter gear was seen in "Spock's Brain," when the landing party beamed down to the glaciated planet and Kirk ordered them to "Set temperatures to 72," which they did by fiddling with some unseen controls on their waists.
Anyway, whenever the idea of the life-support belts showed up, the point is that they weren't actually used in "The Tholian Web," which makes it problematic to intermix the third season and TAS chronologically.
Anyway, whenever the idea of the life-support belts showed up, the point is that they weren't actually used in "The Tholian Web," which makes it problematic to intermix the third season and TAS chronologically.