A commercial HVAC apprentice trains under the supervision of a journey-level HVAC technician to become proficient in the skills and tools required for the job. During your training, you help install, repair, or maintain commercial HVAC and industrial refrigeration systems. Your duties include following blueprints to install heating, ventilation, and air conditioning equipment in commercial buildings. When working on repair jobs, you diagnose the problem and make necessary repairs. You may start the apprenticeships with just observing the experienced technicians complete their work, but eventually, you are given specific tasks to complete with your supervisor. Apprenticeships last approximately three or four years, and you are usually required to take several classes in addition to your on-the-job training.