Yes, on the older ships is a dial type thing in the center of the cabin on the ceiling. As has been said, is an air flow regulator, not a thermostat. But it works really well. If you are at least 5'10 you can reach it easily.
If you leave it wide open and are out late it will get cold, but in the day and after hot showers etc you need to open it up.
There is also a round little vent in the head that sucks air out of the cabin. Is a little strange the first time you see the set up