As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
KCMH - THE CREW REPORTED A STRONG BURNING SMELL WAS COMING FROM THE CABIN AREA DURING FLIGHT. BOTH CABIN AND CREW TEMPERATURE CONTROLS WERE SET AT FULL COLD. MAINTENANCE REMOVED AND REPLACED THE COALESCER SOCK. WHEN GROUND ENGINE RUNS WERE PERFORMED THROUGH ALL PARAMETERS OF BOTH THE HEATING AND COOLING SYSTEM NO BURNING SMELL WAS NOTED. OPERATIONAL AND LEAK CHECKS WERE GOOD. THE AIRCRAFT WAS RETURNED TO SERVICE.