air conditioner vs refrigerator

air conditioner

noun
  • A machine that is used to control temperature and humidity in an enclosed space. 

refrigerator

noun
  • A household appliance used for keeping food fresh by refrigeration (short form fridge). 

  • One who has a chilling influence. 

  • A similar device used to keep non-food items cold, such as blood, photographic film, drugs, or pharmaceuticals like insulin. 

How often have the words air conditioner and refrigerator occurred in a corpus of books? (source: Google Ngram Viewer )