The faster the molecular motion the higher the temperature. The slower the molecular motion the colder the temperature. Absolute zero is that point where all molecular motion ceases. In order to have hot or cold molecules must be present. A vacuum is a condition of nothingness where there are no molecules.
Vacuums exist in degrees.
Some scientists tell us that there is no such thing as an absolute vacuum. Space is the closest thing to an absolute vacuum that is known to us. A vacuum is a perfect insulator. Radiation of all types will travel through a vacuum but will not affect the vacuum. In fact the radiant heat of the sun has no affect whatsoever until it strikes matter.