Like everyone else said, since it is a very old model, it would need a cooling system so it would not overheat, and maybe cool down the user as well, becuase remember, this is a desert. :toughninja:
Just to make sure everyone knows this. "Very old" is a relative term. It could be as young as 40 years old, compared to T-51b suits which are at best 203 years old and T-45d suits which are even older than that. Advanced Power Armor was made by the Enclave after the bombs fell. It's technologically more advanced than any other model series of powered armor.
Is it ever explicitly said that the radiation symbol was a radiation symbol? Being only a couple of pixels high, it could very easily have been a fan. ('sides, there's a whole bunch of Fallout 2 staff who worked for New Vegas, so I'd think they'd know!)
I like the design. It's about a million times better than it was in the beta screenshots.
The original back. Just to post it.
http://i.imgur.com/cYcEd.jpg
This really isn't that big an issue for me. It's just one of those things that bugs me a bit.