At 0946 PSC received calls for a fire in the parking garage of a high rise building. First arriving units went on scene with light smoke showing and the WFD was sounded. E837 arrived as dispatched(third due engine). Upon arrival E837 was flagged down with residents saying there was a fire in the garage. E837 found an HVAC unit and other contents on fire inside the parking garage garage and extinguished the same. E837 operated for approximately 1 hour before returning to service.