Refrigeration Mechanics make, install, repair and service residential, commercial and industrial cooling and heating systems. Some work in building maintenance - for example, servicing the air conditioning systems in high-rise office buildings. Others specialize in repairing small, portable Refrigeration and freezing units.
http://www.itabc.ca/program/refrigeration-and-air-conditioni...

A refrigeration technician is responsible for servicing and installing refrigeration systems for homes, delivery trucks, as well as commercial buildings. Sometimes a technician may specialize in working with large industrial-size refrigeration systems, home units, or walk-in coolers. Refrigeration technicians may become certified in specific areas such as ventilation, HVAC systems, and heating. These engineers typically enter the field after they have completed a two-year training program at a community colleges or vocational school.
http://masterpieceblog.co.uk/what-does-a-refrigeration-techn...