U.S. Air Force Staff Sgt. Michael Murphy II, 633rd Civil Engineer Squadron heating, ventilation and air conditioning craftsman, Airman 1st Class William Davey, 633rd CES HVAC apprentice, troubleshoot a chiller March 19, 2012, at Langley Air Force Base, Va. Troubleshooting allows HVAC Airmen to properly identify a problem within a system without disassembling it. (U.S. Air Force photo by Senior Airman Stephanie Rubi/Released)