Design complete mechanical systems as per the project and client requirements. Do calculations and select the right equipment based on required capacity. Prepare drawings like GA, layouts, schematics, ducting and piping drawings. Select equipment and prepare its technical specifications. Design ducting and piping routes wherever required. Prepare design reports and technical documents explaining how the system will work. Check architectural/project drawings and understand equipment and space requirements. Make sure the design is practical and can actually be installed at the site. Follow required standards/codes like IS, ASHRAE, NBC, SMACNA, ISO, etc.