What was found
PILOT REPORTED SMELL OF SMOKE IN COCKPIT, WHEN PILOT TURNED AIR CONDITION OFF AND CABIN FAN ON PRIOR TO TAKEOFF. TAXIED BACK TO MAIN, REMOVED OVERHEAD PANEL, FOUND WIRING TO AIR CONDITION/FAN SWITCH BURNED. REMOVED SWITCH, FOUND TERMINAL FOR FAN CIRCUIT LOOSE ON SWITCH. FOUND LOOSE TERMINAL, HAD MOVED AND CONTACTED OTHER TERMINAL CAUSING SHORT. (K)