Possible Clues:

• Need defrosting
• Freeze, as a plane's wings
• Single vessel touring centre of Siberia should become frozen
• Become dangerous for driving
• Frees, by the sound of it E.C.I.
• Become slippery in winter, in a way
• Glaciate, e.g.
• Requiring defrosting
• Freeze when I go to church at university
• Make navigation difficult