Senses
忽冷忽热/ 忽冷忽熱 now cold now hot
Sudden changes of temperature; now hot and now cold.
忽冷忽热/ 忽冷忽熱 fickle
To alternate between friendliness and indifference; describing someone whose attitude or affection changes unpredictably
忽冷忽热/ 忽冷忽熱 to blow hot and cold
To work or act by fits and starts; describing someone who lacks perseverance or consistency in their tasks