evaporative cooler vs swamp cooler

evaporative cooler

noun
  • Synonym of swamp cooler 

swamp cooler

noun
  • An evaporative cooling device; a device that cools air by blowing it through or across a moist pad or membrane. 

How often have the words evaporative cooler and swamp cooler occurred in a corpus of books? (source: Google Ngram Viewer )