“If you placed ice in a bell jar and began to pump out the air, any air trapped within the ice would leak out, but as the ice is already ice, it would not change its volume. Alternatively, a pocket of air could get trapped within the ice causing it to explode as the pressure in the air pocket would be greater than that in the bell jar. Otherwise, ice in a vacuum is just the same as ice any where else.”
(Source: ScienceNet)

Without heat, ice remains ice.

“We all know that if you heat water up, it will boil. What you may not know is that the temperature at which water (or any liquid) will boil depends on the atmospheric pressure. Water actually boils at a lower temperature if the pressure around it is lowered. This is why if you go to a high altitude location (like many parts of New Mexico), where the atmospheric pressure is lower, water will boil at slightly less than 100 degrees C.

“In a vacuum chamber, the pressure can be extremely low. So low, in fact, that water can actually boil at room temperature.

“So, if you put some water in a high-vacuum chamber you will see it boil. (Then, with all that water vapor around, it won't be a high vacuum anymore!)”
(Source: University of Illinois -- Physics Van, Outreach Program)

Boiling point of water is 100 degrees C at sea level (approximately, varying with barometric pressure).

We played with this in high school, way back in the dark ages.
;^)

As far as the formation of ice in a micro-G vacuum, far from heat, say at around the Universal average of approx. 2 degrees K, that would be something to see. Elemental oxygen and hydrogen coming together to form crystals. No, air pressure would not be required, otherwise comets wouldn't work nearly as well as they do.

Dan