Heat will always have a movement vector if it's touching something. The transfer of heat from one medium to another itself is already the vector. The summoner mightn't have created such a vector, and intended the heat to simply be there, but by touching another medium (eg skin), heat is conducted away, hence a flow of energy, therefore, a vector.

And since it's a vector, Accelerator can resist this flow of heat, transferring any heat from the surface of his skin to whereever it came from, be it the ground he's standing on or the air around him.

I talked about the "removing body temperature" thing because you mentioned freezing