Run Hot And Cold Meaning

(idiomatic) To alternate between two opposite extremes, such as enthusiasm and disinterest or success and failure.

Example:   Henrietta's feelings for Delbert run hot and cold--one minute she's hopelessly in love with him, and the next she can't stand the sight of him.
  The business runs hot and cold; some months our firm doesn't earn enough to cover expenses and other months, we net 400% profits.
2013 May 23, Sarah Lyall, "British Leader’s Liberal Turn Sets Off a Rebellion in His Party," New York Times (retrieved 29 May 2013):
  London’s right-leaning newspapers, which tend to run hot and cold on the prime minister, are veering toward Arctic right now.