Inside the home, the thermostat continuously monitors the indoor air. When the thermostat determines that the air is getting too hot, it signals the indoor and outdoor units to turn on. When the indoor fan kicks on, it suctions hot air from the home into the return air ducts. The air is then filtered to remove particulate matter.
Then, the air passes over the evaporator coil. This coil contains liquid refrigerant. The liquid refrigerant converts to a gas as it absorbs the heat from the air. This process chills the air by transferring the heat to the refrigerant. Then, the blower fan pushes the chilled air into the ductwork. From there, it can be distributed throughout the home.