37 Repair or maintenance of electronic machines and apparatus; providing information relating to the repair or maintenance of electronic machines and apparatus; electric appliance installation and repair; installation, maintenance and repair of air conditioning apparatus; maintenance of air conditioners; routine servicing of air conditioning apparatus; retrofitting of heating, ventilating and air conditioning installations in buildings; installation, maintenance and repair of air freshening apparatus; maintenance of telecommunication machines and implements; installation of air purifiers; maintenance of range of hoods for household purposes; installation and repair of heating, ventilating and air conditioning systems; installation, maintenance and repair of ventilating apparatus; installation, maintenance and repair of electrical and electronic apparatus and equipment; providing information relating to the repair or maintenance of electric cooking apparatus and installations; air purifying apparatus and machines cleaning; cleaning of heating and cooling machines and apparatus; range hood cleaning services; air duct cleaning services; disinfecting and washing of air conditioners