Your heating, ventilation, and air conditioning (HVAC) system is responsible for keeping your home comfortable throughout the day. An HVAC system is also important for cleaning the air of allergens and dust. The air is pulled from inside your house through a filter, enters into the HVAC system, and is then redistributed to different parts of your house. That system is fairly complex and tends to run pretty much constantly throughout the year. Because of those factors, it can malfunction. There are some signs that you need HVAC system repair.