Unusual sound -- Loud and weird noises may imply that the system needs a replacement fan or condensate pump, or another component. http://pt.thefreedictionary.com/_/cite.aspx?url=http%3a%2f%2fwolf-donaldson-2.mdwrite.net%2Fexactly-how-air-purification-solution-incorporate-with-modern-air-conditioner-equipments&word=rengue&sources=novopt