A/C Cooling Tower Rooftop air conditioning machinery is exposed to the elements; intrusion of water or debris can lead to electrical short circuits or mechanical damage. Rooftop units may require a crane to replace equipment at greater expense. While most hospitals have central air conditioning systems, small rooftop units may also be used to supplement specific hospital areas not covered by the central system. © 2004 The Hartford Steam Boiler Insurance and Inspection Company.     All rights reserved.