HVAC systems are used to control indoor temperature and humidity. These systems use air sent from a compressor to be heated, cooled, and dehumidified. It then travels through registers or ducts to enter the space. Some systems utilize a network of ducts to move the air, while others simply direct the air directly into the room.

Working as an HVAC technician involves a variety of tasks and requires a wide variety of skills. HVAC technicians are often required to manage their own time, travel to various job sites, and work in all types of weather. They must be flexible, able to work under difficult conditions, and have strong problem-solving skills.

HVAC systems have a long history, going back more than a thousand years. These systems have been used by Egyptians, Greeks, Romans, Chinese, and Indians. Earlier HVAC systems used human-powered fans and ropes, or hypocaust furnaces that distributed heat using chimneys and flues.

While some states do not require specialized HVAC licensing, many employers prefer employees with some post-secondary training. One program in Florida offers an HVAC program that prepares students for entry-level HVAC positions in as little as 10 months. This hands-on training covers topics such as basic electricity, motors, refrigeration, duct design, and troubleshooting.

In addition to heating and cooling, HVAC systems can control indoor humidity and dust levels. In order to control indoor air quality, HVAC systems must remove air contaminants.