Performs skilled analysis and repair of commercial-level air conditioning (HVAC) systems; Leads others in highly skilled fabrication or modifications of existing or proposed equipment, facilities, systems or their components from verbal directions, sketches, plans, engineering drawings or technical references; Inspects, services and maintains assigned tools, equipment and vehicles; Performs quality control analysis on equipment or supported systems for proper functioning and performs remedial actions necessary to assure optimum operations; Inspects, approves or certifies work of others (if certified or authorized to do so); Maintains comprehensive activity, operations, service and usage records on supported equipment and systems; Prepares oral and written activity reports; Prepares estimates for unique or complex operations, maintenance and special projects from rough sketches and engineering plans or drawings, and documents use and expenditure of materials, supplies and equipment; Prepares sketches and drawings for work proposed or in-progress to communicate needed information to supervisors, subordinates and contractors; Coordinates own or work-unit activities with other work-units, agencies or contractors to assure optimal use of available resources and to minimize disruptions of service or support; Monitors contractor performance (including contractor-supplied goods and services); Conducts on-the-job training for employees in assigned work-unit; Stores, handles, uses and disposes of hazardous materials required, encountered or generated in work activities; Maintains security and accountability for all tools, equipment and materials, particularly for work in medical, law enforcement, detention or correctional settings; Maintains and uses safety and personal protective equipment; Implements work-site traffic control procedures to ensure safety; Explains rules, regulations or procedures to the public and other County employees for use of County facilities; Collects, labels, transports and analyzes samples of fluids, solids, effluents, etc., encountered in work. Some positions require the ability to: lift and carry up to seventy-five pounds; safely operate assigned vehicles and other powered equipment; work in extremes of heat, humidity, dust, cold; safely wear required safety clothing/equipment; work with on in the presence of obnoxious odors; work with noxious or potentially hazardous chemicals, compounds or products; ascend and descend ladders and stairs to reach and work upon elevated or below-grade work platforms and job sites; differentiate between colors.