freeze up

Short definition from Wiktionary

Verb

1. 1
   To be adversely affected by ice, and not function.
2. 2
   (of machines and software) To come or bring to a sudden halt, stop working (functioning).
3. 3
   (of people and other animals) To stop or be stopped due to attentiveness, fear, surprise, etc.
4. 4
   To become cold and formal in demeanour.

Noun

1. 1
   The blocking of pipes due to freezing.
2. 2
   A period of extremely cold, freezing weather.
3. 3
   The start of the time when surface waters are frozen over.