There are three distinct types of muscles: skeletal muscles, cardiac or heart muscles, and smooth (non-striated) muscles.
HVAC technicians are responsible for the installation, maintenance and repair of heating, ventilation and air conditioning (HVAC) systems. As an HVAC technician, your job duties may include inspecting existing systems and making recommendations intended to improve the efficiency and/or safety of that system's performance. HVAC-R techs may also work on refrigeration systems.
HVACR technicians inspect and maintain heating and cooling systems. Heating, air conditioning, and refrigeration mechanics and installers held about 292,000 jobs in 2014, of which 63 percent were in the plumbing, heating, and air conditioning contractors industry. About 1 in 10 were self-employed in 2014.