ambient temperature would gradually cool to approximately minus 470 degrees F. depending on earths position in it's seasonal Orbit path would dictate how long the residual heat would last until it bleeds off to space. the only heat would be undersea volcanic vents that keep a little of the ocean liquid. all other ocean would freeze completely solid forever
If the sun disappears forever, the temperature will drop at the higher rate as the water level freezes out of the atmosphere. This will cause the entire globe to cool to hundreds of degrees below zero causing most humans as well as most life on the world to freeze to death.