The most used central HVAC system is known as a split system, which includes both outdoor cabinet (which contains the condenser coil and compressor), and an indoor evaporator coil, (This coil is usually installed along with your air handler or your furnace. The compressor pumps out a refrigerant chemical through the entire system.

Once warm air inside your house interacts with the indoor evaporator coil, the heat energy from this interaction is transferred to the refrigerant chemical inside the coil. That process, “cools” the air. The aforementioned refrigerant chemical is then pumped back to the indoor compressor where the cycle starts all over again. The heat that is absorbed by the refrigerant chemical is moved outside your house while conditioned cooler air is blown inside through your ductwork. Another benefit is moisture that is in the air and contributes to humidity is also taken out of the air.

Your heating and cooling systems are usually combined into one system that way they can share the duct work in the home.  Otherwise you would need 2 separate duct work systems in your home, one for the heating system and the other for the cooling system.