I had a hospital call me one time. it was middle of august, and they were getting ready to start sending patients elsewhere it was so hot inside the building. This was at ten pm. I mobilized four men, and found the place was indeed hot. vavs not working, chiller running like crap, air handlers putting out like eighty degree air. Sent one guy to the air compressors to find out what was going on. No air pressure in main leaving boiler room. sent another to look at the air handler to jack all the chilled water valves to half open, and the two of us went to the chiller. Found head pressure control valve stuck closed (ten inch butterfly). cut linkage off, and used a forty eight inch pipe wrench with cheater to open it. wired it open. got chiller running half decent, but clearly dirty condenser. found prv station on pneumatics blown relief leaking air all over. Fortunately I knew where all of this crap was since WE USED TO service it. apparently the new contractor who had the service for only two years didnt do a thing, or care to for that matter. once we got the chiller stabilized, the wind for the controls stabilized, and the air handlers running half decent, we started on the vavs. two months later we had something. this stuff happens a lot, its how you handle it that seperates the men from the boys.