Click this link to view O*NET’s Tasks section for Heating and Air Conditioning Mechanics and Installers. Note that common tasks are listed toward the top, and less common tasks are listed toward the bottom. According to O*NET, what are some common tasks Heating and Air Conditioning Mechanics and Installers perform? Select four options. Discussions with users to verify heating or cooling system malfunctions pumping oil from a well into a pipeline for transmission overseeing the activities of workers in a hydroelectric power plant installing, connecting, or adjusting thermostats, humidistats, or timers. Repairing or replacing defective equipment, components, or wiring. Testing electrical circuits or components.