What was found
IAH- FLIGHT 3442 NOTED SMOKE WARNING ON MAP, FOLLOWED BY #2 PACK FAIL IN FLIGHT. RAN QRH ON BOTHWARNINGS, AND, RETURNED TO IAH. BOTH WARNINGS CLEARED ON RETURN TO IAH. IAH- MAINTENANCE TIGHTENED CLAMPS ON NUMBER 2 HEAT EXCHANGER,PERFORMED A OPERATIONAL CHECK OF THE AIR CONDITIONING SYSTEM, NO DEFECTS NOTED, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.