Geno, the tractor cabs are pretty warm with the heater off. IME.
A/C is an absolute requirement, though - think "Pheasant Under Glass" if you will !
I'm sure it is a requirement in an enclosed rig.
If I can ever get my '85 MF construction tractor going again it won't have that issue. You can just catch a peek of the Gannon box on the back in the picture of the driveway. No cab on that one. Has been a bit chilly the few times I did use it removing snow. Warm clothes help, and I know how to do that........from experience.