advisory services relating to the installation of heating and cooling apparatus; installation, maintenance and repair of apparatus for heating, purifying air, refrigerating, drying, ventilating, temperature control and air-conditioning; cleaning of air-conditioning apparatus; installation, maintenance and repair of electrical and electronic apparatus and equipment; installation, maintenance and repair of air-conditioning systems; construction services relating to the installation of heating, ventilating and air-conditioning systems; advisory services relating to the installation, maintenance and repair of mechanical and electrical equipment