What was found
LGA FLT 938, EN ROUTE CLT TO LGA. AFTER TAKEOFF, A -HOT AIR- ODOR WAS NOTICED IN BOTH THE CABIN AND COCKPIT. THE APU WAS OFF AT THE TIME. WHEN THE LEFT AIR PACK WAS TURNED OFF, THE ODOR BECAME WORSE. THE PACKS WERE RECONFIGURED AND THE FLIGHT CONTINUED TO LGA. FLIGHT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE PLACED THE TRIM AIR VALVES ON MEL, AND RELEASED THE AIRCRAFT FOR SERVICE. MAINTENANCE REPLACED THE AFT TRIM AIR VALVE. LEAK CHECKS OK.