Yep. They are only connected to the A/C system, and that only via two small hoses. Your heat options are floor vents or dash vents.

In many cases the hoses to the center vents have come disconnected so there isn't much air flow. Some details at the link below. Even with them properly connected you don't get a lot of A/C out of them, but it's better than nothing.

http://www.alfabb.com/bb/forums/spider-1966-up/12550-fix-ac-center-vents-not-blowing-90-spider.html

 

thanks for the confirmation.

that is kind of strange that they don't work in the middle.

my AC is working great right now.