When your air conditioning system is running during a humid summer day—and we get plenty of those in Chicagoland—you’ll occasionally hear a dripping sound coming from the unit. This isn’t because the AC uses water to help cool down the house. The only type of cooling system that does that is an evaporative cooler. What you’re hearing is the water moisture the air conditioner has drawn out of the air with the evaporator coil dripping down into a condensate pan and then being drained outside through a condensate drain line. This collection of moisture is a natural result of the evaporator coil absorbing heat from inside the house to cool the air.
This makes it sound like the air conditioner is also a dehumidifier. But this is not really the case. An air conditioner on its own usually isn’t sufficient to properly dehumidify a house. It can provide cooling to help you feel cooler, but when the relative humidity is above 60%, the AC won’t do much to lower it to comfortable levels.