Operate, maintain, and troubleshoot air handling units serving classified and unclassified spaces, including supply and return fans, VFDs, chilled water and hot water coils, reheat, humidification, dehumidification, economizers, and control and isolation dampers. Perform refrigeration maintenance and repair on DX systems, split systems, condensing units, and chilled water equipment, including compressor, metering device, and refrigerant circuit troubleshooting using superheat and subcooling analysis.