The HVAC system provides heating, ventilation and AC for your house. The heating portion could be forced air, radiant, or geothermal. Ventilation could be provided by forced air, or by fans and open windows. This helps airflow and regulate the humidity of your home. Air conditioners could be forced air, split or ductless. Forced air is also known as central air. No matter what the type of AC they all evaporate a refrigerant as they absorb and expel heat from your home.
Read more: Understanding Your HVAC System: Heating, Air Conditioning & Ventilation