A clogged air conditioner condensate drain line is a major cause of serious water damage in homes every summer.
Your central A/C not only cools the air inside your house, it also removes humidity. On a humid day, water vapor extracted from the air by the evaporator coil turns to gallons of liquid condensate that collects in the wide, shallow drip pan underneath the indoor air handler. As long as the condensate drain line flows freely, water is conveyed safely into the household drain system.
evaporator coil , preventative maintenance , condensate drain , service and maintenance
There's no better example of the idea that improvements in technology produce savings than in modern advances in HVAC technology. Perhaps the most productive advancements in residential systems is the variable-speed air handler. In 
An evaporator coil inspection may reveal the hidden secret behind your air conditioner’s 
When 